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 <sect1 id="release-9-0-23">
  <title>Release 9.0.23</title>

  <note>
  <title>Release Date</title>
  <simpara>2015-10-08</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 9.0.22.
   For information about new features in the 9.0 major release, see
   <xref linkend="release-9-0">.
  </para>

  <para>
   This is expected to be the last <productname>PostgreSQL</> release
   in the 9.0.X series.  Users are encouraged to update to a newer
   release branch soon.
  </para>

  <sect2>
   <title>Migration to Version 9.0.23</title>

   <para>
    A dump/restore is not required for those running 9.0.X.
   </para>

   <para>
    However, if you are upgrading from a version earlier than 9.0.18,
    see <xref linkend="release-9-0-18">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Fix <filename>contrib/pgcrypto</> to detect and report
      too-short <function>crypt()</> salts (Josh Kupershmidt)
     </para>

     <para>
      Certain invalid salt arguments crashed the server or disclosed a few
      bytes of server memory.  We have not ruled out the viability of
      attacks that arrange for presence of confidential information in the
      disclosed bytes, but they seem unlikely.  (CVE-2015-5288)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix subtransaction cleanup after a portal (cursor) belonging to an
      outer subtransaction fails (Tom Lane, Michael Paquier)
     </para>

     <para>
      A function executed in an outer-subtransaction cursor could cause an
      assertion failure or crash by referencing a relation created within an
      inner subtransaction.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix insertion of relations into the relation cache <quote>init file</>
      (Tom Lane)
     </para>

     <para>
      An oversight in a patch in the most recent minor releases
      caused <structname>pg_trigger_tgrelid_tgname_index</> to be omitted
      from the init file.  Subsequent sessions detected this, then deemed the
      init file to be broken and silently ignored it, resulting in a
      significant degradation in session startup time.  In addition to fixing
      the bug, install some guards so that any similar future mistake will be
      more obvious.
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid O(N^2) behavior when inserting many tuples into a SPI query
      result (Neil Conway)
     </para>
    </listitem>

    <listitem>
     <para>
      Improve <command>LISTEN</> startup time when there are many unread
      notifications (Matt Newell)
     </para>
    </listitem>

    <listitem>
     <para>
      Disable SSL renegotiation by default (Michael Paquier, Andres Freund)
     </para>

     <para>
      While use of SSL renegotiation is a good idea in theory, we have seen
      too many bugs in practice, both in the underlying OpenSSL library and
      in our usage of it.  Renegotiation will be removed entirely in 9.5 and
      later.  In the older branches, just change the default value
      of <varname>ssl_renegotiation_limit</> to zero (disabled).
     </para>
    </listitem>

    <listitem>
     <para>
      Lower the minimum values of the <literal>*_freeze_max_age</> parameters
      (Andres Freund)
     </para>

     <para>
      This is mainly to make tests of related behavior less time-consuming,
      but it may also be of value for installations with limited disk space.
     </para>
    </listitem>

    <listitem>
     <para>
      Limit the maximum value of <varname>wal_buffers</> to 2GB to avoid
      server crashes (Josh Berkus)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix rare internal overflow in multiplication of <type>numeric</> values
      (Dean Rasheed)
     </para>
    </listitem>

    <listitem>
     <para>
      Guard against hard-to-reach stack overflows involving record types,
      range types, <type>json</>, <type>jsonb</>, <type>tsquery</>,
      <type>ltxtquery</> and <type>query_int</> (Noah Misch)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix handling of <literal>DOW</> and <literal>DOY</> in datetime input
      (Greg Stark)
     </para>

     <para>
      These tokens aren't meant to be used in datetime values, but previously
      they resulted in opaque internal error messages rather
      than <quote>invalid input syntax</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Add more query-cancel checks to regular expression matching (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Add recursion depth protections to regular expression, <literal>SIMILAR
      TO</>, and <literal>LIKE</> matching (Tom Lane)
     </para>

     <para>
      Suitable search patterns and a low stack depth limit could lead to
      stack-overrun crashes.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix potential infinite loop in regular expression execution (Tom Lane)
     </para>

     <para>
      A search pattern that can apparently match a zero-length string, but
      actually doesn't match because of a back reference, could lead to an
      infinite loop.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix low-memory failures in regular expression compilation
      (Andreas Seltenreich)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix low-probability memory leak during regular expression execution
      (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix rare low-memory failure in lock cleanup during transaction abort
      (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <quote>unexpected out-of-memory situation during sort</> errors
      when using tuplestores with small <varname>work_mem</> settings (Tom
      Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix very-low-probability stack overrun in <function>qsort</> (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <quote>invalid memory alloc request size</> failure in hash joins
      with large <varname>work_mem</> settings (Tomas Vondra, Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix assorted planner bugs (Tom Lane)
     </para>

     <para>
      These mistakes could lead to incorrect query plans that would give wrong
      answers, or to assertion failures in assert-enabled builds, or to odd
      planner errors such as <quote>could not devise a query plan for the
      given query</>, <quote>could not find pathkey item to
      sort</>, <quote>plan should not reference subplan's variable</>,
      or <quote>failed to assign all NestLoopParams to plan nodes</>.
      Thanks are due to Andreas Seltenreich and Piotr Stefaniak for fuzz
      testing that exposed these problems.
     </para>
    </listitem>

    <listitem>
     <para>
      Use fuzzy path cost tiebreaking rule in all supported branches (Tom Lane)
     </para>

     <para>
      This change is meant to avoid platform-specific behavior when
      alternative plan choices have effectively-identical estimated costs.
     </para>
    </listitem>

    <listitem>
     <para>
      During postmaster shutdown, ensure that per-socket lock files are
      removed and listen sockets are closed before we remove
      the <filename>postmaster.pid</> file (Tom Lane)
     </para>

     <para>
      This avoids race-condition failures if an external script attempts to
      start a new postmaster as soon as <literal>pg_ctl stop</> returns.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix postmaster's handling of a startup-process crash during crash
      recovery (Tom Lane)
     </para>

     <para>
      If, during a crash recovery cycle, the startup process crashes without
      having restored database consistency, we'd try to launch a new startup
      process, which typically would just crash again, leading to an infinite
      loop.
     </para>
    </listitem>

    <listitem>
     <para>
      Do not print a <literal>WARNING</> when an autovacuum worker is already
      gone when we attempt to signal it, and reduce log verbosity for such
      signals (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent autovacuum launcher from sleeping unduly long if the server
      clock is moved backwards a large amount (&Aacute;lvaro Herrera)
     </para>
    </listitem>

    <listitem>
     <para>
      Ensure that cleanup of a GIN index's pending-insertions list is
      interruptable by cancel requests (Jeff Janes)
     </para>
    </listitem>

    <listitem>
     <para>
      Allow all-zeroes pages in GIN indexes to be reused (Heikki Linnakangas)
     </para>

     <para>
      Such a page might be left behind after a crash.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix off-by-one error that led to otherwise-harmless warnings
      about <quote>apparent wraparound</> in subtrans/multixact truncation
      (Thomas Munro)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix misreporting of <command>CONTINUE</> and <command>MOVE</> statement
      types in <application>PL/pgSQL</>'s error context messages
      (Pavel Stehule, Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix some places in <application>PL/Tcl</> that neglected to check for
      failure of <function>malloc()</> calls (Michael Paquier, &Aacute;lvaro
      Herrera)
     </para>
    </listitem>

    <listitem>
     <para>
      Improve <application>libpq</>'s handling of out-of-memory conditions
      (Michael Paquier, Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix memory leaks and missing out-of-memory checks
      in <application>ecpg</> (Michael Paquier)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>psql</>'s code for locale-aware formatting of numeric
      output (Tom Lane)
     </para>

     <para>
      The formatting code invoked by <literal>\pset numericlocale on</>
      did the wrong thing for some uncommon cases such as numbers with an
      exponent but no decimal point.  It could also mangle already-localized
      output from the <type>money</> data type.
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent crash in <application>psql</>'s <command>\c</> command when
      there is no current connection (Noah Misch)
     </para>
    </listitem>

    <listitem>
     <para>
      Ensure that temporary files created during a <application>pg_dump</>
      run with <acronym>tar</>-format output are not world-readable (Michael
      Paquier)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>pg_dump</> and <application>pg_upgrade</> to support
      cases where the <literal>postgres</> or <literal>template1</> database
      is in a non-default tablespace (Marti Raudsepp, Bruce Momjian)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>pg_dump</> to handle object privileges sanely when
      dumping from a server too old to have a particular privilege type
      (Tom Lane)
     </para>

     <para>
      When dumping functions or procedural languages from pre-7.3
      servers, <application>pg_dump</> would
      produce <command>GRANT</>/<command>REVOKE</> commands that revoked the
      owner's grantable privileges and instead granted all privileges
      to <literal>PUBLIC</>.  Since the privileges involved are
      just <literal>USAGE</> and <literal>EXECUTE</>, this isn't a security
      problem, but it's certainly a surprising representation of the older
      systems' behavior.  Fix it to leave the default privilege state alone
      in these cases.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>pg_dump</> to dump shell types (Tom Lane)
     </para>

     <para>
      Shell types (that is, not-yet-fully-defined types) aren't useful for
      much, but nonetheless <application>pg_dump</> should dump them.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix spinlock assembly code for PPC hardware to be compatible
      with <acronym>AIX</>'s native assembler (Tom Lane)
     </para>

     <para>
      Building with <application>gcc</> didn't work if <application>gcc</>
      had been configured to use the native assembler, which is becoming more
      common.
     </para>
    </listitem>

    <listitem>
     <para>
      On <acronym>AIX</>, test the <literal>-qlonglong</> compiler option
      rather than just assuming it's safe to use (Noah Misch)
     </para>
    </listitem>

    <listitem>
     <para>
      On <acronym>AIX</>, use <literal>-Wl,-brtllib</> link option to allow
      symbols to be resolved at runtime (Noah Misch)
     </para>

     <para>
      Perl relies on this ability in 5.8.0 and later.
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid use of inline functions when compiling with
      32-bit <application>xlc</>, due to compiler bugs (Noah Misch)
     </para>
    </listitem>

    <listitem>
     <para>
      Use <filename>librt</> for <function>sched_yield()</> when necessary,
      which it is on some Solaris versions (Oskari Saarenmaa)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix Windows <filename>install.bat</> script to handle target directory
      names that contain spaces (Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      Make the numeric form of the <productname>PostgreSQL</> version number
      (e.g., <literal>90405</>) readily available to extension Makefiles,
      as a variable named <varname>VERSION_NUM</> (Michael Paquier)
     </para>
    </listitem>

    <listitem>
     <para>
      Update time zone data files to <application>tzdata</> release 2015g for
      DST law changes in Cayman Islands, Fiji, Moldova, Morocco, Norfolk
      Island, North Korea, Turkey, and Uruguay.  There is a new zone name
      <literal>America/Fort_Nelson</> for the Canadian Northern Rockies.
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-9-0-22">
  <title>Release 9.0.22</title>

  <note>
  <title>Release Date</title>
  <simpara>2015-06-12</simpara>
  </note>

  <para>
   This release contains a small number of fixes from 9.0.21.
   For information about new features in the 9.0 major release, see
   <xref linkend="release-9-0">.
  </para>

  <para>
   The <productname>PostgreSQL</> community will stop releasing updates
   for the 9.0.X release series in September 2015.
   Users are encouraged to update to a newer release branch soon.
  </para>

  <sect2>
   <title>Migration to Version 9.0.22</title>

   <para>
    A dump/restore is not required for those running 9.0.X.
   </para>

   <para>
    However, if you are upgrading from a version earlier than 9.0.18,
    see <xref linkend="release-9-0-18">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Fix rare failure to invalidate relation cache init file (Tom Lane)
     </para>

     <para>
      With just the wrong timing of concurrent activity, a <command>VACUUM
      FULL</> on a system catalog might fail to update the <quote>init file</>
      that's used to avoid cache-loading work for new sessions.  This would
      result in later sessions being unable to access that catalog at all.
      This is a very ancient bug, but it's so hard to trigger that no
      reproducible case had been seen until recently.
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid deadlock between incoming sessions and <literal>CREATE/DROP
      DATABASE</> (Tom Lane)
     </para>

     <para>
      A new session starting in a database that is the target of
      a <command>DROP DATABASE</> command, or is the template for
      a <command>CREATE DATABASE</> command, could cause the command to wait
      for five seconds and then fail, even if the new session would have
      exited before that.
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-9-0-21">
  <title>Release 9.0.21</title>

  <note>
  <title>Release Date</title>
  <simpara>2015-06-04</simpara>
  </note>

  <para>
   This release contains a small number of fixes from 9.0.20.
   For information about new features in the 9.0 major release, see
   <xref linkend="release-9-0">.
  </para>

  <para>
   The <productname>PostgreSQL</> community will stop releasing updates
   for the 9.0.X release series in September 2015.
   Users are encouraged to update to a newer release branch soon.
  </para>

  <sect2>
   <title>Migration to Version 9.0.21</title>

   <para>
    A dump/restore is not required for those running 9.0.X.
   </para>

   <para>
    However, if you are upgrading from a version earlier than 9.0.18,
    see <xref linkend="release-9-0-18">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Avoid failures while <function>fsync</>'ing data directory during
      crash restart (Abhijit Menon-Sen, Tom Lane)
     </para>

     <para>
      In the previous minor releases we added a patch to <function>fsync</>
      everything in the data directory after a crash.  Unfortunately its
      response to any error condition was to fail, thereby preventing the
      server from starting up, even when the problem was quite harmless.
      An example is that an unwritable file in the data directory would
      prevent restart on some platforms; but it is common to make SSL
      certificate files unwritable by the server.  Revise this behavior so
      that permissions failures are ignored altogether, and other types of
      failures are logged but do not prevent continuing.
     </para>
    </listitem>

    <listitem>
     <para>
      Remove <application>configure</>'s check prohibiting linking to a
      threaded <application>libpython</>
      on <systemitem class="osname">OpenBSD</> (Tom Lane)
     </para>

     <para>
      The failure this restriction was meant to prevent seems to not be a
      problem anymore on current <systemitem class="osname">OpenBSD</>
      versions.
     </para>
    </listitem>

    <listitem>
     <para>
      Allow <application>libpq</> to use TLS protocol versions beyond v1
      (Noah Misch)
     </para>

     <para>
      For a long time, <application>libpq</> was coded so that the only SSL
      protocol it would allow was TLS v1.  Now that newer TLS versions are
      becoming popular, allow it to negotiate the highest commonly-supported
      TLS version with the server.  (<productname>PostgreSQL</> servers were
      already capable of such negotiation, so no change is needed on the
      server side.)  This is a back-patch of a change already released in
      9.4.0.
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-9-0-20">
  <title>Release 9.0.20</title>

  <note>
  <title>Release Date</title>
  <simpara>2015-05-22</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 9.0.19.
   For information about new features in the 9.0 major release, see
   <xref linkend="release-9-0">.
  </para>

  <para>
   The <productname>PostgreSQL</> community will stop releasing updates
   for the 9.0.X release series in September 2015.
   Users are encouraged to update to a newer release branch soon.
  </para>

  <sect2>
   <title>Migration to Version 9.0.20</title>

   <para>
    A dump/restore is not required for those running 9.0.X.
   </para>

   <para>
    However, if you are upgrading from a version earlier than 9.0.18,
    see <xref linkend="release-9-0-18">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Avoid possible crash when client disconnects just before the
      authentication timeout expires (Benkocs Norbert Attila)
     </para>

     <para>
      If the timeout interrupt fired partway through the session shutdown
      sequence, SSL-related state would be freed twice, typically causing a
      crash and hence denial of service to other sessions.  Experimentation
      shows that an unauthenticated remote attacker could trigger the bug
      somewhat consistently, hence treat as security issue.
      (CVE-2015-3165)
     </para>
    </listitem>

    <listitem>
     <para>
      Improve detection of system-call failures (Noah Misch)
     </para>

     <para>
      Our replacement implementation of <function>snprintf()</> failed to
      check for errors reported by the underlying system library calls;
      the main case that might be missed is out-of-memory situations.
      In the worst case this might lead to information exposure, due to our
      code assuming that a buffer had been overwritten when it hadn't been.
      Also, there were a few places in which security-relevant calls of other
      system library functions did not check for failure.
     </para>

     <para>
      It remains possible that some calls of the <function>*printf()</>
      family of functions are vulnerable to information disclosure if an
      out-of-memory error occurs at just the wrong time.  We judge the risk
      to not be large, but will continue analysis in this area.
      (CVE-2015-3166)
     </para>
    </listitem>

    <listitem>
     <para>
      In <filename>contrib/pgcrypto</>, uniformly report decryption failures
      as <quote>Wrong key or corrupt data</> (Noah Misch)
     </para>

     <para>
      Previously, some cases of decryption with an incorrect key could report
      other error message texts.  It has been shown that such variance in
      error reports can aid attackers in recovering keys from other systems.
      While it's unknown whether <filename>pgcrypto</>'s specific behaviors
      are likewise exploitable, it seems better to avoid the risk by using a
      one-size-fits-all message.
      (CVE-2015-3167)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix incorrect checking of deferred exclusion constraints after a HOT
      update (Tom Lane)
     </para>

     <para>
      If a new row that potentially violates a deferred exclusion constraint
      is HOT-updated (that is, no indexed columns change and the row can be
      stored back onto the same table page) later in the same transaction,
      the exclusion constraint would be reported as violated when the check
      finally occurred, even if the row(s) the new row originally conflicted
      with had been deleted.
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent improper reordering of antijoins (NOT EXISTS joins) versus
      other outer joins (Tom Lane)
     </para>

     <para>
      This oversight in the planner has been observed to cause <quote>could
      not find RelOptInfo for given relids</> errors, but it seems possible
      that sometimes an incorrect query plan might get past that consistency
      check and result in silently-wrong query output.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix incorrect matching of subexpressions in outer-join plan nodes
      (Tom Lane)
     </para>

     <para>
      Previously, if textually identical non-strict subexpressions were used
      both above and below an outer join, the planner might try to re-use
      the value computed below the join, which would be incorrect because the
      executor would force the value to NULL in case of an unmatched outer row.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix GEQO planner to cope with failure of its join order heuristic
      (Tom Lane)
     </para>

     <para>
      This oversight has been seen to lead to <quote>failed to join all
      relations together</> errors in queries involving <literal>LATERAL</>,
      and that might happen in other cases as well.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possible deadlock at startup
      when <literal>max_prepared_transactions</> is too small
      (Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      Don't archive useless preallocated WAL files after a timeline switch
      (Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid <quote>cannot GetMultiXactIdMembers() during recovery</> error
      (&Aacute;lvaro Herrera)
     </para>
    </listitem>

    <listitem>
     <para>
      Recursively <function>fsync()</> the data directory after a crash
      (Abhijit Menon-Sen, Robert Haas)
     </para>

     <para>
      This ensures consistency if another crash occurs shortly later.  (The
      second crash would have to be a system-level crash, not just a database
      crash, for there to be a problem.)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix autovacuum launcher's possible failure to shut down, if an error
      occurs after it receives SIGTERM (&Aacute;lvaro Herrera)
     </para>
    </listitem>

    <listitem>
     <para>
      Cope with unexpected signals in <function>LockBufferForCleanup()</>
      (Andres Freund)
     </para>

     <para>
      This oversight could result in spurious errors about <quote>multiple
      backends attempting to wait for pincount 1</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid waiting for WAL flush or synchronous replication during commit of
      a transaction that was read-only so far as the user is concerned
      (Andres Freund)
     </para>

     <para>
      Previously, a delay could occur at commit in transactions that had
      written WAL due to HOT page pruning, leading to undesirable effects
      such as sessions getting stuck at startup if all synchronous replicas
      are down.  Sessions have also been observed to get stuck in catchup
      interrupt processing when using synchronous replication; this will fix
      that problem as well.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix crash when manipulating hash indexes on temporary tables
      (Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possible failure during hash index bucket split, if other processes
      are modifying the index concurrently (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Check for interrupts while analyzing index expressions (Jeff Janes)
     </para>

     <para>
      <command>ANALYZE</> executes index expressions many times; if there are
      slow functions in such an expression, it's desirable to be able to
      cancel the <command>ANALYZE</> before that loop finishes.
     </para>
    </listitem>

    <listitem>
     <para>
      Add the name of the target server to object description strings for
      foreign-server user mappings (&Aacute;lvaro Herrera)
     </para>
    </listitem>

    <listitem>
     <para>
      Recommend setting <literal>include_realm</> to 1 when using
      Kerberos/GSSAPI/SSPI authentication (Stephen Frost)
     </para>

     <para>
      Without this, identically-named users from different realms cannot be
      distinguished.  For the moment this is only a documentation change, but
      it will become the default setting in <productname>PostgreSQL</> 9.5.
     </para>
    </listitem>

    <listitem>
     <para>
      Remove code for matching IPv4 <filename>pg_hba.conf</> entries to
      IPv4-in-IPv6 addresses (Tom Lane)
     </para>

     <para>
      This hack was added in 2003 in response to a report that some Linux
      kernels of the time would report IPv4 connections as having
      IPv4-in-IPv6 addresses.  However, the logic was accidentally broken in
      9.0.  The lack of any field complaints since then shows that it's not
      needed anymore.  Now we have reports that the broken code causes
      crashes on some systems, so let's just remove it rather than fix it.
      (Had we chosen to fix it, that would make for a subtle and potentially
      security-sensitive change in the effective meaning of
      IPv4 <filename>pg_hba.conf</> entries, which does not seem like a good
      thing to do in minor releases.)
     </para>
    </listitem>

    <listitem>
     <para>
      While shutting down service on Windows, periodically send status
      updates to the Service Control Manager to prevent it from killing the
      service too soon; and ensure that <application>pg_ctl</> will wait for
      shutdown (Krystian Bigaj)
     </para>
    </listitem>

    <listitem>
     <para>
      Reduce risk of network deadlock when using <application>libpq</>'s
      non-blocking mode (Heikki Linnakangas)
     </para>

     <para>
      When sending large volumes of data, it's important to drain the input
      buffer every so often, in case the server has sent enough response data
      to cause it to block on output.  (A typical scenario is that the server
      is sending a stream of NOTICE messages during <literal>COPY FROM
      STDIN</>.)  This worked properly in the normal blocking mode, but not
      so much in non-blocking mode.  We've modified <application>libpq</>
      to opportunistically drain input when it can, but a full defense
      against this problem requires application cooperation: the application
      should watch for socket read-ready as well as write-ready conditions,
      and be sure to call <function>PQconsumeInput()</> upon read-ready.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix array handling in <application>ecpg</> (Michael Meskes)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>psql</> to sanely handle URIs and conninfo strings as
      the first parameter to <command>\connect</>
      (David Fetter, Andrew Dunstan, &Aacute;lvaro Herrera)
     </para>

     <para>
      This syntax has been accepted (but undocumented) for a long time, but
      previously some parameters might be taken from the old connection
      instead of the given string, which was agreed to be undesirable.
     </para>
    </listitem>

    <listitem>
     <para>
      Suppress incorrect complaints from <application>psql</> on some
      platforms that it failed to write <filename>~/.psql_history</> at exit
      (Tom Lane)
     </para>

     <para>
      This misbehavior was caused by a workaround for a bug in very old
      (pre-2006) versions of <application>libedit</>.  We fixed it by
      removing the workaround, which will cause a similar failure to appear
      for anyone still using such versions of <application>libedit</>.
      Recommendation: upgrade that library, or use <application>libreadline</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>pg_dump</>'s rule for deciding which casts are
      system-provided casts that should not be dumped (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix dumping of views that are just <literal>VALUES(...)</> but have
      column aliases (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      In <application>pg_upgrade</>, force timeline 1 in the new cluster
      (Bruce Momjian)
     </para>

     <para>
      This change prevents upgrade failures caused by bogus complaints about
      missing WAL history files.
     </para>
    </listitem>

    <listitem>
     <para>
      In <application>pg_upgrade</>, check for improperly non-connectable
      databases before proceeding
      (Bruce Momjian)
     </para>
    </listitem>

    <listitem>
     <para>
      In <application>pg_upgrade</>, quote directory paths
      properly in the generated <literal>delete_old_cluster</> script
      (Bruce Momjian)
     </para>
    </listitem>

    <listitem>
     <para>
      In <application>pg_upgrade</>, preserve database-level freezing info
      properly
      (Bruce Momjian)
     </para>

     <para>
      This oversight could cause missing-clog-file errors for tables within
      the <literal>postgres</> and <literal>template1</> databases.
     </para>
    </listitem>

    <listitem>
     <para>
      Run <application>pg_upgrade</> and <application>pg_resetxlog</> with
      restricted privileges on Windows, so that they don't fail when run by
      an administrator (Muhammad Asif Naeem)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix slow sorting algorithm in <filename>contrib/intarray</> (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix compile failure on Sparc V8 machines (Rob Rowan)
     </para>
    </listitem>

    <listitem>
     <para>
      Update time zone data files to <application>tzdata</> release 2015d
      for DST law changes in Egypt, Mongolia, and Palestine, plus historical
      changes in Canada and Chile.  Also adopt revised zone abbreviations for
      the America/Adak zone (HST/HDT not HAST/HADT).
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-9-0-19">
  <title>Release 9.0.19</title>

  <note>
  <title>Release Date</title>
  <simpara>2015-02-05</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 9.0.18.
   For information about new features in the 9.0 major release, see
   <xref linkend="release-9-0">.
  </para>

  <sect2>
   <title>Migration to Version 9.0.19</title>

   <para>
    A dump/restore is not required for those running 9.0.X.
   </para>

   <para>
    However, if you are upgrading from a version earlier than 9.0.18,
    see <xref linkend="release-9-0-18">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Fix buffer overruns in <function>to_char()</>
      (Bruce Momjian)
     </para>

     <para>
      When <function>to_char()</> processes a numeric formatting template
      calling for a large number of digits, <productname>PostgreSQL</>
      would read past the end of a buffer.  When processing a crafted
      timestamp formatting template, <productname>PostgreSQL</> would write
      past the end of a buffer.  Either case could crash the server.
      We have not ruled out the possibility of attacks that lead to
      privilege escalation, though they seem unlikely.
      (CVE-2015-0241)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix buffer overrun in replacement <function>*printf()</> functions
      (Tom Lane)
     </para>

     <para>
      <productname>PostgreSQL</> includes a replacement implementation
      of <function>printf</> and related functions.  This code will overrun
      a stack buffer when formatting a floating point number (conversion
      specifiers <literal>e</>, <literal>E</>, <literal>f</>, <literal>F</>,
      <literal>g</> or <literal>G</>) with requested precision greater than
      about 500.  This will crash the server, and we have not ruled out the
      possibility of attacks that lead to privilege escalation.
      A database user can trigger such a buffer overrun through
      the <function>to_char()</> SQL function.  While that is the only
      affected core <productname>PostgreSQL</> functionality, extension
      modules that use printf-family functions may be at risk as well.
     </para>

     <para>
      This issue primarily affects <productname>PostgreSQL</> on Windows.
      <productname>PostgreSQL</> uses the system implementation of these
      functions where adequate, which it is on other modern platforms.
      (CVE-2015-0242)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix buffer overruns in <filename>contrib/pgcrypto</>
      (Marko Tiikkaja, Noah Misch)
     </para>

     <para>
      Errors in memory size tracking within the <filename>pgcrypto</>
      module permitted stack buffer overruns and improper dependence on the
      contents of uninitialized memory.  The buffer overrun cases can
      crash the server, and we have not ruled out the possibility of
      attacks that lead to privilege escalation.
      (CVE-2015-0243)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possible loss of frontend/backend protocol synchronization after
      an error
      (Heikki Linnakangas)
     </para>

     <para>
      If any error occurred while the server was in the middle of reading a
      protocol message from the client, it could lose synchronization and
      incorrectly try to interpret part of the message's data as a new
      protocol message.  An attacker able to submit crafted binary data
      within a command parameter might succeed in injecting his own SQL
      commands this way.  Statement timeout and query cancellation are the
      most likely sources of errors triggering this scenario.  Particularly
      vulnerable are applications that use a timeout and also submit
      arbitrary user-crafted data as binary query parameters.  Disabling
      statement timeout will reduce, but not eliminate, the risk of
      exploit.  Our thanks to Emil Lenngren for reporting this issue.
      (CVE-2015-0244)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix information leak via constraint-violation error messages
      (Stephen Frost)
     </para>

     <para>
      Some server error messages show the values of columns that violate
      a constraint, such as a unique constraint.  If the user does not have
      <literal>SELECT</> privilege on all columns of the table, this could
      mean exposing values that the user should not be able to see.  Adjust
      the code so that values are displayed only when they came from the SQL
      command or could be selected by the user.
      (CVE-2014-8161)
     </para>
    </listitem>

    <listitem>
     <para>
      Lock down regression testing's temporary installations on Windows
      (Noah Misch)
     </para>

     <para>
      Use SSPI authentication to allow connections only from the OS user
      who launched the test suite.  This closes on Windows the same
      vulnerability previously closed on other platforms, namely that other
      users might be able to connect to the test postmaster.
      (CVE-2014-0067)
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid possible data corruption if <command>ALTER DATABASE SET
      TABLESPACE</> is used to move a database to a new tablespace and then
      shortly later move it back to its original tablespace (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid corrupting tables when <command>ANALYZE</> inside a transaction
      is rolled back (Andres Freund, Tom Lane, Michael Paquier)
     </para>

     <para>
      If the failing transaction had earlier removed the last index, rule, or
      trigger from the table, the table would be left in a corrupted state
      with the relevant <structname>pg_class</> flags not set though they
      should be.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix use-of-already-freed-memory problem in EvalPlanQual processing
      (Tom Lane)
     </para>

     <para>
      In <literal>READ COMMITTED</> mode, queries that lock or update
      recently-updated rows could crash as a result of this bug.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix planning of <command>SELECT FOR UPDATE</> when using a partial
      index on a child table (Kyotaro Horiguchi)
     </para>

     <para>
      In <literal>READ COMMITTED</> mode, <command>SELECT FOR UPDATE</> must
      also recheck the partial index's <literal>WHERE</> condition when
      rechecking a recently-updated row to see if it still satisfies the
      query's <literal>WHERE</> condition.  This requirement was missed if the
      index belonged to an inheritance child table, so that it was possible
      to incorrectly return rows that no longer satisfy the query condition.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix corner case wherein <command>SELECT FOR UPDATE</> could return a row
      twice, and possibly miss returning other rows (Tom Lane)
     </para>

     <para>
      In <literal>READ COMMITTED</> mode, a <command>SELECT FOR UPDATE</>
      that is scanning an inheritance tree could incorrectly return a row
      from a prior child table instead of the one it should return from a
      later child table.
     </para>
    </listitem>

    <listitem>
     <para>
      Reject duplicate column names in the referenced-columns list of
      a <literal>FOREIGN KEY</> declaration (David Rowley)
     </para>

     <para>
      This restriction is per SQL standard.  Previously we did not reject
      the case explicitly, but later on the code would fail with
      bizarre-looking errors.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix bugs in raising a <type>numeric</> value to a large integral power
      (Tom Lane)
     </para>

     <para>
      The previous code could get a wrong answer, or consume excessive
      amounts of time and memory before realizing that the answer must
      overflow.
     </para>
    </listitem>

    <listitem>
     <para>
      In <function>numeric_recv()</>, truncate away any fractional digits
      that would be hidden according to the value's <literal>dscale</> field
      (Tom Lane)
     </para>

     <para>
      A <type>numeric</> value's display scale (<literal>dscale</>) should
      never be less than the number of nonzero fractional digits; but
      apparently there's at least one broken client application that
      transmits binary <type>numeric</> values in which that's true.
      This leads to strange behavior since the extra digits are taken into
      account by arithmetic operations even though they aren't printed.
      The least risky fix seems to be to truncate away such <quote>hidden</>
      digits on receipt, so that the value is indeed what it prints as.
     </para>
    </listitem>

    <listitem>
     <para>
      Reject out-of-range numeric timezone specifications (Tom Lane)
     </para>

     <para>
      Simple numeric timezone specifications exceeding +/- 168 hours (one
      week) would be accepted, but could then cause null-pointer dereference
      crashes in certain operations.  There's no use-case for such large UTC
      offsets, so reject them.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix bugs in <type>tsquery</> <literal>@&gt;</> <type>tsquery</>
      operator (Heikki Linnakangas)
     </para>

     <para>
      Two different terms would be considered to match if they had the same
      CRC.  Also, if the second operand had more terms than the first, it
      would be assumed not to be contained in the first; which is wrong
      since it might contain duplicate terms.
     </para>
    </listitem>

    <listitem>
     <para>
      Improve ispell dictionary's defenses against bad affix files (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Allow more than 64K phrases in a thesaurus dictionary (David Boutin)
     </para>

     <para>
      The previous coding could crash on an oversize dictionary, so this was
      deemed a back-patchable bug fix rather than a feature addition.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix namespace handling in <function>xpath()</> (Ali Akbar)
     </para>

     <para>
      Previously, the <type>xml</> value resulting from
      an <function>xpath()</> call would not have namespace declarations if
      the namespace declarations were attached to an ancestor element in the
      input <type>xml</> value, rather than to the specific element being
      returned.  Propagate the ancestral declaration so that the result is
      correct when considered in isolation.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix planner problems with nested append relations, such as inherited
      tables within <literal>UNION ALL</> subqueries (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fail cleanly when a GiST index tuple doesn't fit on a page, rather
      than going into infinite recursion (Andrew Gierth)
     </para>
    </listitem>

    <listitem>
     <para>
      Exempt tables that have per-table <varname>cost_limit</>
      and/or <varname>cost_delay</> settings from autovacuum's global cost
      balancing rules (&Aacute;lvaro Herrera)
     </para>

     <para>
      The previous behavior resulted in basically ignoring these per-table
      settings, which was unintended.  Now, a table having such settings
      will be vacuumed using those settings, independently of what is going
      on in other autovacuum workers.  This may result in heavier total I/O
      load than before, so such settings should be re-examined for sanity.
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid wholesale autovacuuming when autovacuum is nominally off
      (Tom Lane)
     </para>

     <para>
      Even when autovacuum is nominally off, we will still launch autovacuum
      worker processes to vacuum tables that are at risk of XID wraparound.
      However, such a worker process then proceeded to vacuum all tables in
      the target database, if they met the usual thresholds for
      autovacuuming.  This is at best pretty unexpected; at worst it delays
      response to the wraparound threat.  Fix it so that if autovacuum is
      turned off, workers <emphasis>only</> do anti-wraparound vacuums and
      not any other work.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix race condition between hot standby queries and replaying a
      full-page image (Heikki Linnakangas)
     </para>

     <para>
      This mistake could result in transient errors in queries being
      executed in hot standby.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix several cases where recovery logic improperly ignored WAL records
      for <literal>COMMIT/ABORT PREPARED</> (Heikki Linnakangas)
     </para>

     <para>
      The most notable oversight was
      that <varname>recovery_min_apply_delay</> failed to delay application
      of a two-phase commit.
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid creating unnecessary <filename>.ready</> marker files for
      timeline history files (Fujii Masao)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possible null pointer dereference when an empty prepared statement
      is used and the <varname>log_statement</> setting is <literal>mod</>
      or <literal>ddl</> (Fujii Masao)
     </para>
    </listitem>

    <listitem>
     <para>
      Change <quote>pgstat wait timeout</> warning message to be LOG level,
      and rephrase it to be more understandable (Tom Lane)
     </para>

     <para>
      This message was originally thought to be essentially a can't-happen
      case, but it occurs often enough on our slower buildfarm members to be
      a nuisance.  Reduce it to LOG level, and expend a bit more effort on
      the wording: it now reads <quote>using stale statistics instead of
      current ones because stats collector is not responding</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix SPARC spinlock implementation to ensure correctness if the CPU is
      being run in a non-TSO coherency mode, as some non-Solaris kernels do
      (Andres Freund)
     </para>
    </listitem>

    <listitem>
     <para>
      Warn if OS X's <function>setlocale()</> starts an unwanted extra
      thread inside the postmaster (Noah Misch)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix processing of repeated <literal>dbname</> parameters
      in <function>PQconnectdbParams()</> (Alex Shulgin)
     </para>

     <para>
      Unexpected behavior ensued if the first occurrence
      of <literal>dbname</> contained a connection string or URI to be
      expanded.
     </para>
    </listitem>

    <listitem>
     <para>
      Ensure that <application>libpq</> reports a suitable error message on
      unexpected socket EOF (Marko Tiikkaja, Tom Lane)
     </para>

     <para>
      Depending on kernel behavior, <application>libpq</> might return an
      empty error string rather than something useful when the server
      unexpectedly closed the socket.
     </para>
    </listitem>

    <listitem>
     <para>
      Clear any old error message during <function>PQreset()</>
      (Heikki Linnakangas)
     </para>

     <para>
      If <function>PQreset()</> is called repeatedly, and the connection
      cannot be re-established, error messages from the failed connection
      attempts kept accumulating in the <structname>PGconn</>'s error
      string.
     </para>
    </listitem>

    <listitem>
     <para>
      Properly handle out-of-memory conditions while parsing connection
      options in <application>libpq</> (Alex Shulgin, Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix array overrun in <application>ecpg</>'s version
      of <function>ParseDateTime()</> (Michael Paquier)
     </para>
    </listitem>

    <listitem>
     <para>
      In <application>initdb</>, give a clearer error message if a password
      file is specified but is empty (Mats Erik Andersson)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>psql</>'s <command>\s</> command to work nicely with
      libedit, and add pager support (Stepan Rutz, Tom Lane)
     </para>

     <para>
      When using libedit rather than readline, <command>\s</> printed the
      command history in a fairly unreadable encoded format, and on recent
      libedit versions might fail altogether.  Fix that by printing the
      history ourselves rather than having the library do it.  A pleasant
      side-effect is that the pager is used if appropriate.
     </para>

     <para>
      This patch also fixes a bug that caused newline encoding to be applied
      inconsistently when saving the command history with libedit.
      Multiline history entries written by older <application>psql</>
      versions will be read cleanly with this patch, but perhaps not
      vice versa, depending on the exact libedit versions involved.
     </para>
    </listitem>

    <listitem>
     <para>
      Improve consistency of parsing of <application>psql</>'s special
      variables (Tom Lane)
     </para>

     <para>
      Allow variant spellings of <literal>on</> and <literal>off</> (such
      as <literal>1</>/<literal>0</>) for <literal>ECHO_HIDDEN</>
      and <literal>ON_ERROR_ROLLBACK</>.  Report a warning for unrecognized
      values for <literal>COMP_KEYWORD_CASE</>, <literal>ECHO</>,
      <literal>ECHO_HIDDEN</>, <literal>HISTCONTROL</>,
      <literal>ON_ERROR_ROLLBACK</>, and <literal>VERBOSITY</>.  Recognize
      all values for all these variables case-insensitively; previously
      there was a mishmash of case-sensitive and case-insensitive behaviors.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>psql</>'s expanded-mode display to work
      consistently when using <literal>border</> = 3
      and <literal>linestyle</> = <literal>ascii</> or <literal>unicode</>
      (Stephen Frost)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possible deadlock during parallel restore of a schema-only dump
      (Robert Haas, Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix core dump in <literal>pg_dump --binary-upgrade</> on zero-column
      composite type (Rushabh Lathia)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix block number checking
      in <filename>contrib/pageinspect</>'s <function>get_raw_page()</>
      (Tom Lane)
     </para>

     <para>
      The incorrect checking logic could prevent access to some pages in
      non-main relation forks.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <filename>contrib/pgcrypto</>'s <function>pgp_sym_decrypt()</>
      to not fail on messages whose length is 6 less than a power of 2
      (Marko Tiikkaja)
     </para>
    </listitem>

    <listitem>
     <para>
      Handle unexpected query results, especially NULLs, safely in
      <filename>contrib/tablefunc</>'s <function>connectby()</>
      (Michael Paquier)
     </para>

     <para>
      <function>connectby()</> previously crashed if it encountered a NULL
      key value.  It now prints that row but doesn't recurse further.
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid a possible crash in <filename>contrib/xml2</>'s
      <function>xslt_process()</> (Mark Simonetti)
     </para>

     <para>
      <application>libxslt</> seems to have an undocumented dependency on
      the order in which resources are freed; reorder our calls to avoid a
      crash.
     </para>
    </listitem>

    <listitem>
     <para>
      Numerous cleanups of warnings from Coverity static code analyzer
      (Andres Freund, Tatsuo Ishii, Marko Kreen, Tom Lane, Michael Paquier)
     </para>

     <para>
      These changes are mostly cosmetic but in some cases fix corner-case
      bugs, for example a crash rather than a proper error report after an
      out-of-memory failure.  None are believed to represent security
      issues.
     </para>
    </listitem>

    <listitem>
     <para>
      Detect incompatible OpenLDAP versions during build (Noah Misch)
     </para>

     <para>
      With OpenLDAP versions 2.4.24 through 2.4.31,
      inclusive, <productname>PostgreSQL</> backends can crash at exit.
      Raise a warning during <application>configure</> based on the
      compile-time OpenLDAP version number, and test the crashing scenario
      in the <filename>contrib/dblink</> regression test.
     </para>
    </listitem>

    <listitem>
     <para>
      In non-MSVC Windows builds, ensure <filename>libpq.dll</> is installed
      with execute permissions (Noah Misch)
     </para>
    </listitem>

    <listitem>
     <para>
      Make <application>pg_regress</> remove any temporary installation it
      created upon successful exit (Tom Lane)
     </para>

     <para>
      This results in a very substantial reduction in disk space usage
      during <literal>make check-world</>, since that sequence involves
      creation of numerous temporary installations.
     </para>
    </listitem>

    <listitem>
     <para>
      Support time zone abbreviations that change UTC offset from time to
      time (Tom Lane)
     </para>

     <para>
      Previously, <productname>PostgreSQL</> assumed that the UTC offset
      associated with a time zone abbreviation (such as <literal>EST</>)
      never changes in the usage of any particular locale.  However this
      assumption fails in the real world, so introduce the ability for a
      zone abbreviation to represent a UTC offset that sometimes changes.
      Update the zone abbreviation definition files to make use of this
      feature in timezone locales that have changed the UTC offset of their
      abbreviations since 1970 (according to the IANA timezone database).
      In such timezones, <productname>PostgreSQL</> will now associate the
      correct UTC offset with the abbreviation depending on the given date.
     </para>
    </listitem>

    <listitem>
     <para>
      Update time zone abbreviations lists (Tom Lane)
     </para>

     <para>
      Add CST (China Standard Time) to our lists.
      Remove references to ADT as <quote>Arabia Daylight Time</>, an
      abbreviation that's been out of use since 2007; therefore, claiming
      there is a conflict with <quote>Atlantic Daylight Time</> doesn't seem
      especially helpful.
      Fix entirely incorrect GMT offsets for CKT (Cook Islands), FJT, and FJST
      (Fiji); we didn't even have them on the proper side of the date line.
     </para>
    </listitem>

    <listitem>
     <para>
      Update time zone data files to <application>tzdata</> release 2015a.
     </para>

     <para>
      The IANA timezone database has adopted abbreviations of the form
      <literal>A<replaceable>x</>ST</literal>/<literal>A<replaceable>x</>DT</literal>
      for all Australian time zones, reflecting what they believe to be
      current majority practice Down Under.  These names do not conflict
      with usage elsewhere (other than ACST for Acre Summer Time, which has
      been in disuse since 1994).  Accordingly, adopt these names into
      our <quote>Default</> timezone abbreviation set.
      The <quote>Australia</> abbreviation set now contains only CST, EAST,
      EST, SAST, SAT, and WST, all of which are thought to be mostly
      historical usage.  Note that SAST has also been changed to be South
      Africa Standard Time in the <quote>Default</> abbreviation set.
     </para>

     <para>
      Also, add zone abbreviations SRET (Asia/Srednekolymsk) and XJT
      (Asia/Urumqi), and use WSST/WSDT for western Samoa.  Also, there were
      DST law changes in Chile, Mexico, the Turks &amp; Caicos Islands
      (America/Grand_Turk), and Fiji.  There is a new zone
      Pacific/Bougainville for portions of Papua New Guinea.  Also, numerous
      corrections for historical (pre-1970) time zone data.
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-9-0-18">
  <title>Release 9.0.18</title>

  <note>
  <title>Release Date</title>
  <simpara>2014-07-24</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 9.0.17.
   For information about new features in the 9.0 major release, see
   <xref linkend="release-9-0">.
  </para>

  <sect2>
   <title>Migration to Version 9.0.18</title>

   <para>
    A dump/restore is not required for those running 9.0.X.
   </para>

   <para>
    However, this release corrects an index corruption problem in some GiST
    indexes.  See the first changelog entry below to find out whether your
    installation has been affected and what steps you should take if so.
   </para>

   <para>
    Also, if you are upgrading from a version earlier than 9.0.15,
    see <xref linkend="release-9-0-15">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Correctly initialize padding bytes in <filename>contrib/btree_gist</>
      indexes on <type>bit</> columns (Heikki Linnakangas)
     </para>

     <para>
      This error could result in incorrect query results due to values that
      should compare equal not being seen as equal.
      Users with GiST indexes on <type>bit</> or <type>bit varying</>
      columns should <command>REINDEX</> those indexes after installing this
      update.
     </para>
    </listitem>

    <listitem>
     <para>
      Protect against torn pages when deleting GIN list pages (Heikki
      Linnakangas)
     </para>

     <para>
      This fix prevents possible index corruption if a system crash occurs
      while the page update is being written to disk.
     </para>
    </listitem>

    <listitem>
     <para>
      Don't clear the right-link of a GiST index page while replaying
      updates from WAL (Heikki Linnakangas)
     </para>

     <para>
      This error could lead to transiently wrong answers from GiST index
      scans performed in Hot Standby.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possibly-incorrect cache invalidation during nested calls
      to <function>ReceiveSharedInvalidMessages</> (Andres Freund)
     </para>
    </listitem>

    <listitem>
     <para>
      Don't assume a subquery's output is unique if there's a set-returning
      function in its targetlist (David Rowley)
     </para>

     <para>
      This oversight could lead to misoptimization of constructs
      like <literal>WHERE x IN (SELECT y, generate_series(1,10) FROM t GROUP
      BY y)</literal>.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix failure to detoast fields in composite elements of structured
      types (Tom Lane)
     </para>

     <para>
      This corrects cases where TOAST pointers could be copied into other
      tables without being dereferenced.  If the original data is later
      deleted, it would lead to errors like <quote>missing chunk number 0
      for toast value ...</> when the now-dangling pointer is used.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <quote>record type has not been registered</> failures with
      whole-row references to the output of Append plan nodes (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possible crash when invoking a user-defined function while
      rewinding a cursor (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix query-lifespan memory leak while evaluating the arguments for a
      function in <literal>FROM</> (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix session-lifespan memory leaks in regular-expression processing
      (Tom Lane, Arthur O'Dwyer, Greg Stark)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix data encoding error in <filename>hungarian.stop</> (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix liveness checks for rows that were inserted in the current
      transaction and then deleted by a now-rolled-back subtransaction
      (Andres Freund)
     </para>

     <para>
      This could cause problems (at least spurious warnings, and at worst an
      infinite loop) if <command>CREATE INDEX</> or <command>CLUSTER</> were
      done later in the same transaction.
     </para>
    </listitem>

    <listitem>
     <para>
      Clear <structname>pg_stat_activity</>.<structfield>xact_start</>
      during <command>PREPARE TRANSACTION</> (Andres Freund)
     </para>

     <para>
      After the <command>PREPARE</>, the originating session is no longer in
      a transaction, so it should not continue to display a transaction
      start time.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <command>REASSIGN OWNED</> to not fail for text search objects
      (&Aacute;lvaro Herrera)
     </para>
    </listitem>

    <listitem>
     <para>
      Block signals during postmaster startup (Tom Lane)
     </para>

     <para>
      This ensures that the postmaster will properly clean up after itself
      if, for example, it receives <systemitem>SIGINT</> while still
      starting up.
     </para>
    </listitem>

    <listitem>
     <para>
      Secure Unix-domain sockets of temporary postmasters started during
      <literal>make check</> (Noah Misch)
     </para>

     <para>
      Any local user able to access the socket file could connect as the
      server's bootstrap superuser, then proceed to execute arbitrary code as
      the operating-system user running the test, as we previously noted in
      CVE-2014-0067.  This change defends against that risk by placing the
      server's socket in a temporary, mode 0700 subdirectory
      of <filename>/tmp</>.  The hazard remains however on platforms where
      Unix sockets are not supported, notably Windows, because then the
      temporary postmaster must accept local TCP connections.
     </para>

     <para>
      A useful side effect of this change is to simplify
      <literal>make check</> testing in builds that
      override <literal>DEFAULT_PGSOCKET_DIR</>.  Popular non-default values
      like <filename>/var/run/postgresql</> are often not writable by the
      build user, requiring workarounds that will no longer be necessary.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix tablespace creation WAL replay to work on Windows (MauMau)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix detection of socket creation failures on Windows (Bruce Momjian)
     </para>
    </listitem>

    <listitem>
     <para>
      On Windows, allow new sessions to absorb values of PGC_BACKEND
      parameters (such as <xref linkend="guc-log-connections">) from the
      configuration file (Amit Kapila)
     </para>

     <para>
      Previously, if such a parameter were changed in the file post-startup,
      the change would have no effect.
     </para>
    </listitem>

    <listitem>
     <para>
      Properly quote executable path names on Windows (Nikhil Deshpande)
     </para>

     <para>
      This oversight could cause <application>initdb</>
      and <application>pg_upgrade</> to fail on Windows, if the installation
      path contained both spaces and <literal>@</> signs.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix linking of <application>libpython</> on OS X (Tom Lane)
     </para>

     <para>
      The method we previously used can fail with the Python library
      supplied by Xcode 5.0 and later.
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid buffer bloat in <application>libpq</> when the server
      consistently sends data faster than the client can absorb it
      (Shin-ichi Morita, Tom Lane)
     </para>

     <para>
      <application>libpq</> could be coerced into enlarging its input buffer
      until it runs out of memory (which would be reported misleadingly
      as <quote>lost synchronization with server</>).  Under ordinary
      circumstances it's quite far-fetched that data could be continuously
      transmitted more quickly than the <function>recv()</> loop can
      absorb it, but this has been observed when the client is artificially
      slowed by scheduler constraints.
     </para>
    </listitem>

    <listitem>
     <para>
      Ensure that LDAP lookup attempts in <application>libpq</> time out as
      intended (Laurenz Albe)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>ecpg</> to do the right thing when an array
      of <type>char *</> is the target for a FETCH statement returning more
      than one row, as well as some other array-handling fixes
      (Ashutosh Bapat)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>pg_restore</>'s processing of old-style large object
      comments (Tom Lane)
     </para>

     <para>
      A direct-to-database restore from an archive file generated by a
      pre-9.0 version of <application>pg_dump</> would usually fail if the
      archive contained more than a few comments for large objects.
     </para>
    </listitem>

    <listitem>
     <para>
      In <filename>contrib/pgcrypto</> functions, ensure sensitive
      information is cleared from stack variables before returning
      (Marko Kreen)
     </para>
    </listitem>

    <listitem>
     <para>
      In <filename>contrib/uuid-ossp</>, cache the state of the OSSP UUID
      library across calls (Tom Lane)
     </para>

     <para>
      This improves the efficiency of UUID generation and reduces the amount
      of entropy drawn from <filename>/dev/urandom</>, on platforms that
      have that.
     </para>
    </listitem>

    <listitem>
     <para>
      Update time zone data files to <application>tzdata</> release 2014e
      for DST law changes in Crimea, Egypt, and Morocco.
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-9-0-17">
  <title>Release 9.0.17</title>

  <note>
  <title>Release Date</title>
  <simpara>2014-03-20</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 9.0.16.
   For information about new features in the 9.0 major release, see
   <xref linkend="release-9-0">.
  </para>

  <sect2>
   <title>Migration to Version 9.0.17</title>

   <para>
    A dump/restore is not required for those running 9.0.X.
   </para>

   <para>
    However, if you are upgrading from a version earlier than 9.0.15,
    see <xref linkend="release-9-0-15">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Restore GIN metapages unconditionally to avoid torn-page risk
      (Heikki Linnakangas)
     </para>

     <para>
      Although this oversight could theoretically result in a corrupted
      index, it is unlikely to have caused any problems in practice, since
      the active part of a GIN metapage is smaller than a standard 512-byte
      disk sector.
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid race condition in checking transaction commit status during
      receipt of a <command>NOTIFY</> message (Marko Tiikkaja)
     </para>

     <para>
      This prevents a scenario wherein a sufficiently fast client might
      respond to a notification before database updates made by the
      notifier have become visible to the recipient.
     </para>
    </listitem>

    <listitem>
     <para>
      Allow regular-expression operators to be terminated early by query
      cancel requests (Tom Lane)
     </para>

     <para>
      This prevents scenarios wherein a pathological regular expression
      could lock up a server process uninterruptably for a long time.
     </para>
    </listitem>

    <listitem>
     <para>
      Remove incorrect code that tried to allow <literal>OVERLAPS</> with
      single-element row arguments (Joshua Yanovski)
     </para>

     <para>
      This code never worked correctly, and since the case is neither
      specified by the SQL standard nor documented, it seemed better to
      remove it than fix it.
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid getting more than <literal>AccessShareLock</> when de-parsing a
      rule or view (Dean Rasheed)
     </para>

     <para>
      This oversight resulted in <application>pg_dump</> unexpectedly
      acquiring <literal>RowExclusiveLock</> locks on tables mentioned as
      the targets of <literal>INSERT</>/<literal>UPDATE</>/<literal>DELETE</>
      commands in rules.  While usually harmless, that could interfere with
      concurrent transactions that tried to acquire, for example,
      <literal>ShareLock</> on those tables.
     </para>
    </listitem>

    <listitem>
     <para>
      Improve performance of index endpoint probes during planning (Tom Lane)
     </para>

     <para>
      This change fixes a significant performance problem that occurred
      when there were many not-yet-committed rows at the end of the index,
      which is a common situation for indexes on sequentially-assigned
      values such as timestamps or sequence-generated identifiers.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix test to see if hot standby connections can be allowed immediately
      after a crash (Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent interrupts while reporting non-<literal>ERROR</> messages
      (Tom Lane)
     </para>

     <para>
      This guards against rare server-process freezeups due to recursive
      entry to <function>syslog()</>, and perhaps other related problems.
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent intermittent <quote>could not reserve shared memory region</>
      failures on recent Windows versions (MauMau)
     </para>
    </listitem>

    <listitem>
     <para>
      Update time zone data files to <application>tzdata</> release 2014a
      for DST law changes in Fiji and Turkey, plus historical changes in
      Israel and Ukraine.
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-9-0-16">
  <title>Release 9.0.16</title>

  <note>
  <title>Release Date</title>
  <simpara>2014-02-20</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 9.0.15.
   For information about new features in the 9.0 major release, see
   <xref linkend="release-9-0">.
  </para>

  <sect2>
   <title>Migration to Version 9.0.16</title>

   <para>
    A dump/restore is not required for those running 9.0.X.
   </para>

   <para>
    However, if you are upgrading from a version earlier than 9.0.15,
    see <xref linkend="release-9-0-15">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Shore up <literal>GRANT ... WITH ADMIN OPTION</> restrictions
      (Noah Misch)
     </para>

     <para>
      Granting a role without <literal>ADMIN OPTION</> is supposed to
      prevent the grantee from adding or removing members from the granted
      role, but this restriction was easily bypassed by doing <literal>SET
      ROLE</> first.  The security impact is mostly that a role member can
      revoke the access of others, contrary to the wishes of his grantor.
      Unapproved role member additions are a lesser concern, since an
      uncooperative role member could provide most of his rights to others
      anyway by creating views or <literal>SECURITY DEFINER</> functions.
      (CVE-2014-0060)
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent privilege escalation via manual calls to PL validator
      functions (Andres Freund)
     </para>

     <para>
      The primary role of PL validator functions is to be called implicitly
      during <command>CREATE FUNCTION</>, but they are also normal SQL
      functions that a user can call explicitly.  Calling a validator on
      a function actually written in some other language was not checked
      for and could be exploited for privilege-escalation purposes.
      The fix involves adding a call to a privilege-checking function in
      each validator function.  Non-core procedural languages will also
      need to make this change to their own validator functions, if any.
      (CVE-2014-0061)
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid multiple name lookups during table and index DDL
      (Robert Haas, Andres Freund)
     </para>

     <para>
      If the name lookups come to different conclusions due to concurrent
      activity, we might perform some parts of the DDL on a different table
      than other parts.  At least in the case of <command>CREATE INDEX</>,
      this can be used to cause the permissions checks to be performed
      against a different table than the index creation, allowing for a
      privilege escalation attack.
      (CVE-2014-0062)
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent buffer overrun with long datetime strings (Noah Misch)
     </para>

     <para>
      The <literal>MAXDATELEN</> constant was too small for the longest
      possible value of type <type>interval</>, allowing a buffer overrun
      in <function>interval_out()</>.  Although the datetime input
      functions were more careful about avoiding buffer overrun, the limit
      was short enough to cause them to reject some valid inputs, such as
      input containing a very long timezone name.  The <application>ecpg</>
      library contained these vulnerabilities along with some of its own.
      (CVE-2014-0063)
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent buffer overrun due to integer overflow in size calculations
      (Noah Misch, Heikki Linnakangas)
     </para>

     <para>
      Several functions, mostly type input functions, calculated an
      allocation size without checking for overflow.  If overflow did
      occur, a too-small buffer would be allocated and then written past.
      (CVE-2014-0064)
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent overruns of fixed-size buffers
      (Peter Eisentraut, Jozef Mlich)
     </para>

     <para>
      Use <function>strlcpy()</> and related functions to provide a clear
      guarantee that fixed-size buffers are not overrun.  Unlike the
      preceding items, it is unclear whether these cases really represent
      live issues, since in most cases there appear to be previous
      constraints on the size of the input string.  Nonetheless it seems
      prudent to silence all Coverity warnings of this type.
      (CVE-2014-0065)
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid crashing if <function>crypt()</> returns NULL (Honza Horak,
      Bruce Momjian)
     </para>

     <para>
      There are relatively few scenarios in which <function>crypt()</>
      could return NULL, but <filename>contrib/chkpass</> would crash
      if it did.  One practical case in which this could be an issue is
      if <application>libc</> is configured to refuse to execute unapproved
      hashing algorithms (e.g., <quote>FIPS mode</>).
      (CVE-2014-0066)
     </para>
    </listitem>

    <listitem>
     <para>
      Document risks of <literal>make check</> in the regression testing
      instructions (Noah Misch, Tom Lane)
     </para>

     <para>
      Since the temporary server started by <literal>make check</>
      uses <quote>trust</> authentication, another user on the same machine
      could connect to it as database superuser, and then potentially
      exploit the privileges of the operating-system user who started the
      tests.  A future release will probably incorporate changes in the
      testing procedure to prevent this risk, but some public discussion is
      needed first.  So for the moment, just warn people against using
      <literal>make check</> when there are untrusted users on the
      same machine.
      (CVE-2014-0067)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possible mis-replay of WAL records when some segments of a
      relation aren't full size (Greg Stark, Tom Lane)
     </para>

     <para>
      The WAL update could be applied to the wrong page, potentially many
      pages past where it should have been.  Aside from corrupting data,
      this error has been observed to result in significant <quote>bloat</>
      of standby servers compared to their masters, due to updates being
      applied far beyond where the end-of-file should have been.  This
      failure mode does not appear to be a significant risk during crash
      recovery, only when initially synchronizing a standby created from a
      base backup taken from a quickly-changing master.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix bug in determining when recovery has reached consistency
      (Tomonari Katsumata, Heikki Linnakangas)
     </para>

     <para>
      In some cases WAL replay would mistakenly conclude that the database
      was already consistent at the start of replay, thus possibly allowing
      hot-standby queries before the database was really consistent.  Other
      symptoms such as <quote>PANIC: WAL contains references to invalid
      pages</> were also possible.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix improper locking of btree index pages while replaying
      a <literal>VACUUM</> operation in hot-standby mode (Andres Freund,
      Heikki Linnakangas, Tom Lane)
     </para>

     <para>
      This error could result in <quote>PANIC: WAL contains references to
      invalid pages</> failures.
     </para>
    </listitem>

    <listitem>
     <para>
      Ensure that insertions into non-leaf GIN index pages write a full-page
      WAL record when appropriate (Heikki Linnakangas)
     </para>

     <para>
      The previous coding risked index corruption in the event of a
      partial-page write during a system crash.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix race conditions during server process exit (Robert Haas)
     </para>

     <para>
      Ensure that signal handlers don't attempt to use the
      process's <varname>MyProc</> pointer after it's no longer valid.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix unsafe references to <varname>errno</> within error reporting
      logic (Christian Kruse)
     </para>

     <para>
      This would typically lead to odd behaviors such as missing or
      inappropriate <literal>HINT</> fields.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possible crashes from using <function>ereport()</> too early
      during server startup (Tom Lane)
     </para>

     <para>
      The principal case we've seen in the field is a crash if the server
      is started in a directory it doesn't have permission to read.
     </para>
    </listitem>

    <listitem>
     <para>
      Clear retry flags properly in OpenSSL socket write
      function (Alexander Kukushkin)
     </para>

     <para>
      This omission could result in a server lockup after unexpected loss
      of an SSL-encrypted connection.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix length checking for Unicode identifiers (<literal>U&amp;"..."</>
      syntax) containing escapes (Tom Lane)
     </para>

     <para>
      A spurious truncation warning would be printed for such identifiers
      if the escaped form of the identifier was too long, but the
      identifier actually didn't need truncation after de-escaping.
     </para>
    </listitem>

    <listitem>
     <para>
      Allow keywords that are type names to be used in lists of roles
      (Stephen Frost)
     </para>

     <para>
      A previous patch allowed such keywords to be used without quoting
      in places such as role identifiers; but it missed cases where a
      list of role identifiers was permitted, such as <literal>DROP ROLE</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possible crash due to invalid plan for nested sub-selects, such
      as <literal>WHERE (... x IN (SELECT ...) ...) IN (SELECT ...)</>
      (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Ensure that <command>ANALYZE</> creates statistics for a table column
      even when all the values in it are <quote>too wide</> (Tom Lane)
     </para>

     <para>
      <command>ANALYZE</> intentionally omits very wide values from its
      histogram and most-common-values calculations, but it neglected to do
      something sane in the case that all the sampled entries are too wide.
     </para>
    </listitem>

    <listitem>
     <para>
      In <literal>ALTER TABLE ... SET TABLESPACE</>, allow the database's
      default tablespace to be used without a permissions check
      (Stephen Frost)
     </para>

     <para>
      <literal>CREATE TABLE</> has always allowed such usage,
      but <literal>ALTER TABLE</> didn't get the memo.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <quote>cannot accept a set</> error when some arms of
      a <literal>CASE</> return a set and others don't (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix checks for all-zero client addresses in pgstat functions (Kevin
      Grittner)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possible misclassification of multibyte characters by the text
      search parser (Tom Lane)
     </para>

     <para>
      Non-ASCII characters could be misclassified when using C locale with
      a multibyte encoding.  On Cygwin, non-C locales could fail as well.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possible misbehavior in <function>plainto_tsquery()</>
      (Heikki Linnakangas)
     </para>

     <para>
      Use <function>memmove()</> not <function>memcpy()</> for copying
      overlapping memory regions.  There have been no field reports of
      this actually causing trouble, but it's certainly risky.
     </para>
    </listitem>

    <listitem>
     <para>
      Accept <literal>SHIFT_JIS</> as an encoding name for locale checking
      purposes (Tatsuo Ishii)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix misbehavior of <function>PQhost()</> on Windows (Fujii Masao)
     </para>

     <para>
      It should return <literal>localhost</> if no host has been specified.
     </para>
    </listitem>

    <listitem>
     <para>
      Improve error handling in <application>libpq</> and <application>psql</>
      for failures during <literal>COPY TO STDOUT/FROM STDIN</> (Tom Lane)
     </para>

     <para>
      In particular this fixes an infinite loop that could occur in 9.2 and
      up if the server connection was lost during <literal>COPY FROM
      STDIN</>.  Variants of that scenario might be possible in older
      versions, or with other client applications.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix misaligned descriptors in <application>ecpg</> (MauMau)
     </para>
    </listitem>

    <listitem>
     <para>
      In <application>ecpg</>, handle lack of a hostname in the connection
      parameters properly (Michael Meskes)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix performance regression in <filename>contrib/dblink</> connection
      startup (Joe Conway)
     </para>

     <para>
      Avoid an unnecessary round trip when client and server encodings match.
     </para>
    </listitem>

    <listitem>
     <para>
      In <filename>contrib/isn</>, fix incorrect calculation of the check
      digit for ISMN values (Fabien Coelho)
     </para>
    </listitem>

    <listitem>
     <para>
      Ensure client-code-only installation procedure works as documented
      (Peter Eisentraut)
     </para>
    </listitem>

    <listitem>
     <para>
      In Mingw and Cygwin builds, install the <application>libpq</> DLL
      in the <filename>bin</> directory (Andrew Dunstan)
     </para>

     <para>
      This duplicates what the MSVC build has long done.  It should fix
      problems with programs like <application>psql</> failing to start
      because they can't find the DLL.
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid using the deprecated <literal>dllwrap</> tool in Cygwin builds
      (Marco Atzeri)
     </para>
    </listitem>

    <listitem>
     <para>
      Don't generate plain-text <filename>HISTORY</>
      and <filename>src/test/regress/README</> files anymore (Tom Lane)
     </para>

     <para>
      These text files duplicated the main HTML and PDF documentation
      formats.  The trouble involved in maintaining them greatly outweighs
      the likely audience for plain-text format.  Distribution tarballs
      will still contain files by these names, but they'll just be stubs
      directing the reader to consult the main documentation.
      The plain-text <filename>INSTALL</> file will still be maintained, as
      there is arguably a use-case for that.
     </para>
    </listitem>

    <listitem>
     <para>
      Update time zone data files to <application>tzdata</> release 2013i
      for DST law changes in Jordan and historical changes in Cuba.
     </para>

     <para>
      In addition, the zones <literal>Asia/Riyadh87</>,
      <literal>Asia/Riyadh88</>, and <literal>Asia/Riyadh89</> have been
      removed, as they are no longer maintained by IANA, and never
      represented actual civil timekeeping practice.
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-9-0-15">
  <title>Release 9.0.15</title>

  <note>
  <title>Release Date</title>
  <simpara>2013-12-05</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 9.0.14.
   For information about new features in the 9.0 major release, see
   <xref linkend="release-9-0">.
  </para>

  <sect2>
   <title>Migration to Version 9.0.15</title>

   <para>
    A dump/restore is not required for those running 9.0.X.
   </para>

   <para>
    However, this release corrects a number of potential data corruption
    issues.  See the first two changelog entries below to find out whether
    your installation has been affected and what steps you can take if so.
   </para>

   <para>
    Also, if you are upgrading from a version earlier than 9.0.13,
    see <xref linkend="release-9-0-13">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Fix <command>VACUUM</>'s tests to see whether it can
      update <structfield>relfrozenxid</> (Andres Freund)
     </para>

     <para>
      In some cases <command>VACUUM</> (either manual or autovacuum) could
      incorrectly advance a table's <structfield>relfrozenxid</> value,
      allowing tuples to escape freezing, causing those rows to become
      invisible once 2^31 transactions have elapsed.  The probability of
      data loss is fairly low since multiple incorrect advancements would
      need to happen before actual loss occurs, but it's not zero.  Users
      upgrading from releases 9.0.4 or 8.4.8 or earlier are not affected, but
      all later versions contain the bug.
     </para>

     <para>
      The issue can be ameliorated by, after upgrading, vacuuming all tables
      in all databases while having <link
      linkend="guc-vacuum-freeze-table-age"><varname>vacuum_freeze_table_age</></link>
      set to zero.  This will fix any latent corruption but will not be able
      to fix all pre-existing data errors.  However, an installation can be
      presumed safe after performing this vacuuming if it has executed fewer
      than 2^31 update transactions in its lifetime (check this with
      <literal>SELECT txid_current() < 2^31</>).
     </para>
    </listitem>

    <listitem>
     <para>
      Fix initialization of <filename>pg_clog</> and <filename>pg_subtrans</>
      during hot standby startup (Andres Freund, Heikki Linnakangas)
     </para>

     <para>
      This bug can cause data loss on standby servers at the moment they
      start to accept hot-standby queries, by marking committed transactions
      as uncommitted. The likelihood of such corruption is small unless, at
      the time of standby startup, the primary server has executed many
      updating transactions since its last checkpoint.  Symptoms include
      missing rows, rows that should have been deleted being still visible,
      and obsolete versions of updated rows being still visible alongside
      their newer versions.
     </para>

     <para>
      This bug was introduced in versions 9.3.0, 9.2.5, 9.1.10, and 9.0.14.
      Standby servers that have only been running earlier releases are not
      at risk.  It's recommended that standby servers that have ever run any
      of the buggy releases be re-cloned from the primary (e.g., with a new
      base backup) after upgrading.
     </para>
    </listitem>

    <listitem>
     <para>
      Truncate <filename>pg_multixact</> contents during WAL replay
      (Andres Freund)
     </para>

     <para>
      This avoids ever-increasing disk space consumption in standby servers.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix race condition in GIN index posting tree page deletion (Heikki
      Linnakangas)
     </para>

     <para>
      This could lead to transient wrong answers or query failures.
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid flattening a subquery whose <literal>SELECT</> list contains a
      volatile function wrapped inside a sub-<literal>SELECT</> (Tom Lane)
     </para>

     <para>
      This avoids unexpected results due to extra evaluations of the
      volatile function.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix planner's processing of non-simple-variable subquery outputs
      nested within outer joins (Tom Lane)
     </para>

     <para>
      This error could lead to incorrect plans for queries involving
      multiple levels of subqueries within <literal>JOIN</> syntax.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix premature deletion of temporary files (Andres Freund)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possible read past end of memory in rule printing (Peter Eisentraut)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix array slicing of <type>int2vector</> and <type>oidvector</> values
      (Tom Lane)
     </para>

     <para>
      Expressions of this kind are now implicitly promoted to
      regular <type>int2</> or <type>oid</> arrays.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix incorrect behaviors when using a SQL-standard, simple GMT offset
      timezone (Tom Lane)
     </para>

     <para>
      In some cases, the system would use the simple GMT offset value when
      it should have used the regular timezone setting that had prevailed
      before the simple offset was selected.  This change also causes
      the <function>timeofday</> function to honor the simple GMT offset
      zone.
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent possible misbehavior when logging translations of Windows
      error codes (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Properly quote generated command lines in <application>pg_ctl</>
      (Naoya Anzai and Tom Lane)
     </para>

     <para>
      This fix applies only to Windows.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>pg_dumpall</> to work when a source database
      sets <link
      linkend="guc-default-transaction-read-only"><varname>default_transaction_read_only</></link>
      via <command>ALTER DATABASE SET</> (Kevin Grittner)
     </para>

     <para>
      Previously, the generated script would fail during restore.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>ecpg</>'s processing of lists of variables
      declared <type>varchar</> (Zolt&aacute;n B&ouml;sz&ouml;rm&eacute;nyi)
     </para>
    </listitem>

    <listitem>
     <para>
      Make <filename>contrib/lo</> defend against incorrect trigger definitions
      (Marc Cousin)
     </para>
    </listitem>

    <listitem>
     <para>
      Update time zone data files to <application>tzdata</> release 2013h
      for DST law changes in Argentina, Brazil, Jordan, Libya,
      Liechtenstein, Morocco, and Palestine.  Also, new timezone
      abbreviations WIB, WIT, WITA for Indonesia.
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-9-0-14">
  <title>Release 9.0.14</title>

  <note>
  <title>Release Date</title>
  <simpara>2013-10-10</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 9.0.13.
   For information about new features in the 9.0 major release, see
   <xref linkend="release-9-0">.
  </para>

  <sect2>
   <title>Migration to Version 9.0.14</title>

   <para>
    A dump/restore is not required for those running 9.0.X.
   </para>

   <para>
    However, if you are upgrading from a version earlier than 9.0.13,
    see <xref linkend="release-9-0-13">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Prevent corruption of multi-byte characters when attempting to
      case-fold identifiers (Andrew Dunstan)
     </para>

     <para>
      <productname>PostgreSQL</> case-folds non-ASCII characters only
      when using a single-byte server encoding.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix checkpoint memory leak in background writer when <literal>wal_level =
      hot_standby</> (Naoya Anzai)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix memory leak caused by <function>lo_open()</function> failure
      (Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix memory overcommit bug when <varname>work_mem</> is using more
      than 24GB of memory (Stephen Frost)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix deadlock bug in libpq when using SSL (Stephen Frost)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possible SSL state corruption in threaded libpq applications
      (Nick Phillips, Stephen Frost)
     </para>
    </listitem>

    <listitem>
     <para>
      Properly compute row estimates for boolean columns containing many NULL
      values (Andrew Gierth)
     </para>

     <para>
      Previously tests like <literal>col IS NOT TRUE</> and <literal>col IS
      NOT FALSE</> did not properly factor in NULL values when estimating
      plan costs.
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent pushing down <literal>WHERE</> clauses into unsafe
      <literal>UNION/INTERSECT</> subqueries (Tom Lane)
     </para>

     <para>
      Subqueries of a <literal>UNION</> or <literal>INTERSECT</> that
      contain set-returning functions or volatile functions in their
      <literal>SELECT</> lists could be improperly optimized, leading to
      run-time errors or incorrect query results.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix rare case of <quote>failed to locate grouping columns</>
      planner failure (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Improve view dumping code's handling of dropped columns in referenced
      tables (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Properly record index comments created using <literal>UNIQUE</>
      and <literal>PRIMARY KEY</> syntax (Andres Freund)
     </para>

     <para>
      This fixes a parallel <application>pg_restore</> failure.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <command>REINDEX TABLE</> and <command>REINDEX DATABASE</>
      to properly revalidate constraints and mark invalidated indexes as
      valid (Noah Misch)
     </para>

     <para>
      <command>REINDEX INDEX</> has always worked properly.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possible deadlock during concurrent <command>CREATE INDEX
      CONCURRENTLY</> operations (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <function>regexp_matches()</> handling of zero-length matches
      (Jeevan Chalke)
     </para>

     <para>
      Previously, zero-length matches like '^' could return too many matches.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix crash for overly-complex regular expressions (Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix regular expression match failures for back references combined with
      non-greedy quantifiers (Jeevan Chalke)
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent <command>CREATE FUNCTION</> from checking <command>SET</>
      variables unless function body checking is enabled (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Allow <command>ALTER DEFAULT PRIVILEGES</> to operate on schemas
      without requiring CREATE permission (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Loosen restriction on keywords used in queries (Tom Lane)
     </para>

     <para>
      Specifically, lessen keyword restrictions for role names, language
      names, <command>EXPLAIN</> and <command>COPY</> options, and
      <command>SET</> values.  This allows <literal>COPY ... (FORMAT
      BINARY)</> to work as expected; previously <literal>BINARY</> needed
      to be quoted.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <function>pgp_pub_decrypt()</> so it works for secret keys with
      passwords (Marko Kreen)
     </para>
    </listitem>

    <listitem>
     <para>
      Remove rare inaccurate warning during vacuum of index-less tables
      (Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      Ensure that <command>VACUUM ANALYZE</> still runs the ANALYZE phase
      if its attempt to truncate the file is cancelled due to lock conflicts
      (Kevin Grittner)
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid possible failure when performing transaction control commands (e.g
      ROLLBACK) in prepared queries (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Ensure that floating-point data input accepts standard spellings
      of <quote>infinity</> on all platforms (Tom Lane)
     </para>

     <para>
      The C99 standard says that allowable spellings are <literal>inf</>,
      <literal>+inf</>, <literal>-inf</>, <literal>infinity</>,
      <literal>+infinity</>, and <literal>-infinity</>.  Make sure we
      recognize these even if the platform's <function>strtod</> function
      doesn't.
     </para>
    </listitem>

    <listitem>
     <para>
      Expand ability to compare rows to records and arrays (Rafal Rzepecki,
      Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Update time zone data files to <application>tzdata</> release 2013d
      for DST law changes in Israel, Morocco, Palestine, and Paraguay.
      Also, historical zone data corrections for Macquarie Island.
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-9-0-13">
  <title>Release 9.0.13</title>

  <note>
  <title>Release Date</title>
  <simpara>2013-04-04</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 9.0.12.
   For information about new features in the 9.0 major release, see
   <xref linkend="release-9-0">.
  </para>

  <sect2>
   <title>Migration to Version 9.0.13</title>

   <para>
    A dump/restore is not required for those running 9.0.X.
   </para>

   <para>
    However, this release corrects several errors in management of GiST
    indexes.  After installing this update, it is advisable to
    <command>REINDEX</> any GiST indexes that meet one or more of the
    conditions described below.
   </para>

   <para>
    Also, if you are upgrading from a version earlier than 9.0.6,
    see <xref linkend="release-9-0-6">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Fix insecure parsing of server command-line switches (Mitsumasa
      Kondo, Kyotaro Horiguchi)
     </para>

     <para>
      A connection request containing a database name that begins with
      <quote><literal>-</></quote> could be crafted to damage or destroy
      files within the server's data directory, even if the request is
      eventually rejected.  (CVE-2013-1899)
     </para>
    </listitem>

    <listitem>
     <para>
      Reset OpenSSL randomness state in each postmaster child process
      (Marko Kreen)
     </para>

     <para>
      This avoids a scenario wherein random numbers generated by
      <filename>contrib/pgcrypto</> functions might be relatively easy for
      another database user to guess.  The risk is only significant when
      the postmaster is configured with <varname>ssl</> = <literal>on</>
      but most connections don't use SSL encryption.  (CVE-2013-1900)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix GiST indexes to not use <quote>fuzzy</> geometric comparisons when
      it's not appropriate to do so (Alexander Korotkov)
     </para>

     <para>
      The core geometric types perform comparisons using <quote>fuzzy</>
      equality, but <function>gist_box_same</> must do exact comparisons,
      else GiST indexes using it might become inconsistent.  After installing
      this update, users should <command>REINDEX</> any GiST indexes on
      <type>box</>, <type>polygon</>, <type>circle</>, or <type>point</>
      columns, since all of these use <function>gist_box_same</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix erroneous range-union and penalty logic in GiST indexes that use
      <filename>contrib/btree_gist</> for variable-width data types, that is
      <type>text</>, <type>bytea</>, <type>bit</>, and <type>numeric</>
      columns (Tom Lane)
     </para>

     <para>
      These errors could result in inconsistent indexes in which some keys
      that are present would not be found by searches, and also in useless
      index bloat.  Users are advised to <command>REINDEX</> such indexes
      after installing this update.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix bugs in GiST page splitting code for multi-column indexes
      (Tom Lane)
     </para>

     <para>
      These errors could result in inconsistent indexes in which some keys
      that are present would not be found by searches, and also in indexes
      that are unnecessarily inefficient to search.  Users are advised to
      <command>REINDEX</> multi-column GiST indexes after installing this
      update.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <function>gist_point_consistent</>
      to handle fuzziness consistently (Alexander Korotkov)
     </para>

     <para>
      Index scans on GiST indexes on <type>point</> columns would sometimes
      yield results different from a sequential scan, because
      <function>gist_point_consistent</> disagreed with the underlying
      operator code about whether to do comparisons exactly or fuzzily.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix buffer leak in WAL replay (Heikki Linnakangas)
     </para>

     <para>
      This bug could result in <quote>incorrect local pin count</> errors
      during replay, making recovery impossible.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix race condition in <command>DELETE RETURNING</> (Tom Lane)
     </para>

     <para>
      Under the right circumstances, <command>DELETE RETURNING</> could
      attempt to fetch data from a shared buffer that the current process
      no longer has any pin on.  If some other process changed the buffer
      meanwhile, this would lead to garbage <literal>RETURNING</> output, or
      even a crash.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix infinite-loop risk in regular expression compilation (Tom Lane,
      Don Porter)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix potential null-pointer dereference in regular expression compilation
      (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <function>to_char()</> to use ASCII-only case-folding rules where
      appropriate (Tom Lane)
     </para>

     <para>
      This fixes misbehavior of some template patterns that should be
      locale-independent, but mishandled <quote><literal>I</></quote> and
      <quote><literal>i</></quote> in Turkish locales.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix unwanted rejection of timestamp <literal>1999-12-31 24:00:00</>
      (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix logic error when a single transaction does <command>UNLISTEN</>
      then <command>LISTEN</> (Tom Lane)
     </para>

     <para>
      The session wound up not listening for notify events at all, though it
      surely should listen in this case.
     </para>
    </listitem>

    <listitem>
     <para>
      Remove useless <quote>picksplit doesn't support secondary split</> log
      messages (Josh Hansen, Tom Lane)
     </para>

     <para>
      This message seems to have been added in expectation of code that was
      never written, and probably never will be, since GiST's default
      handling of secondary splits is actually pretty good.  So stop nagging
      end users about it.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possible failure to send a session's last few transaction
      commit/abort counts to the statistics collector (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Eliminate memory leaks in PL/Perl's <function>spi_prepare()</> function
      (Alex Hunsaker, Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>pg_dumpall</> to handle database names containing
      <quote><literal>=</></quote> correctly (Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid crash in <application>pg_dump</> when an incorrect connection
      string is given (Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      Ignore invalid indexes in <application>pg_dump</> and
      <application>pg_upgrade</> (Michael Paquier, Bruce Momjian)
     </para>

     <para>
      Dumping invalid indexes can cause problems at restore time, for example
      if the reason the index creation failed was because it tried to enforce
      a uniqueness condition not satisfied by the table's data.  Also, if the
      index creation is in fact still in progress, it seems reasonable to
      consider it to be an uncommitted DDL change, which
      <application>pg_dump</> wouldn't be expected to dump anyway.
      <application>pg_upgrade</> now also skips invalid indexes rather than
      failing.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <filename>contrib/pg_trgm</>'s <function>similarity()</> function
      to return zero for trigram-less strings (Tom Lane)
     </para>

     <para>
      Previously it returned <literal>NaN</> due to internal division by zero.
     </para>
    </listitem>

    <listitem>
     <para>
      Update time zone data files to <application>tzdata</> release 2013b
      for DST law changes in Chile, Haiti, Morocco, Paraguay, and some
      Russian areas.  Also, historical zone data corrections for numerous
      places.
     </para>

     <para>
      Also, update the time zone abbreviation files for recent changes in
      Russia and elsewhere: <literal>CHOT</>, <literal>GET</>,
      <literal>IRKT</>, <literal>KGT</>, <literal>KRAT</>, <literal>MAGT</>,
      <literal>MAWT</>, <literal>MSK</>, <literal>NOVT</>, <literal>OMST</>,
      <literal>TKT</>, <literal>VLAT</>, <literal>WST</>, <literal>YAKT</>,
      <literal>YEKT</> now follow their current meanings, and
      <literal>VOLT</> (Europe/Volgograd) and <literal>MIST</>
      (Antarctica/Macquarie) are added to the default abbreviations list.
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-9-0-12">
  <title>Release 9.0.12</title>

  <note>
  <title>Release Date</title>
  <simpara>2013-02-07</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 9.0.11.
   For information about new features in the 9.0 major release, see
   <xref linkend="release-9-0">.
  </para>

  <sect2>
   <title>Migration to Version 9.0.12</title>

   <para>
    A dump/restore is not required for those running 9.0.X.
   </para>

   <para>
    However, if you are upgrading from a version earlier than 9.0.6,
    see <xref linkend="release-9-0-6">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Prevent execution of <function>enum_recv</> from SQL (Tom Lane)
     </para>

     <para>
      The function was misdeclared, allowing a simple SQL command to crash the
      server.  In principle an attacker might be able to use it to examine the
      contents of server memory.  Our thanks to Sumit Soni (via Secunia SVCRP)
      for reporting this issue.  (CVE-2013-0255)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix multiple problems in detection of when a consistent database
      state has been reached during WAL replay (Fujii Masao, Heikki
      Linnakangas, Simon Riggs, Andres Freund)
     </para>
    </listitem>

    <listitem>
     <para>
      Update minimum recovery point when truncating a relation file (Heikki
      Linnakangas)
     </para>

     <para>
      Once data has been discarded, it's no longer safe to stop recovery at
      an earlier point in the timeline.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix missing cancellations in hot standby mode (Noah Misch, Simon Riggs)
     </para>

     <para>
      The need to cancel conflicting hot-standby queries would sometimes be
      missed, allowing those queries to see inconsistent data.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix SQL grammar to allow subscripting or field selection from a
      sub-SELECT result (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix performance problems with autovacuum truncation in busy workloads
      (Jan Wieck)
     </para>

     <para>
      Truncation of empty pages at the end of a table requires exclusive
      lock, but autovacuum was coded to fail (and release the table lock)
      when there are conflicting lock requests.  Under load, it is easily
      possible that truncation would never occur, resulting in table bloat.
      Fix by performing a partial truncation, releasing the lock, then
      attempting to re-acquire the lock and continue.  This fix also greatly
      reduces the average time before autovacuum releases the lock after a
      conflicting request arrives.
     </para>
    </listitem>

    <listitem>
     <para>
      Protect against race conditions when scanning
      <structname>pg_tablespace</> (Stephen Frost, Tom Lane)
     </para>

     <para>
      <command>CREATE DATABASE</> and <command>DROP DATABASE</> could
      misbehave if there were concurrent updates of
      <structname>pg_tablespace</> entries.
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent <command>DROP OWNED</> from trying to drop whole databases or
      tablespaces (&Aacute;lvaro Herrera)
     </para>

     <para>
      For safety, ownership of these objects must be reassigned, not dropped.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix error in <link
      linkend="guc-vacuum-freeze-table-age"><varname>vacuum_freeze_table_age</></link>
      implementation (Andres Freund)
     </para>

     <para>
      In installations that have existed for more than <link
      linkend="guc-vacuum-freeze-min-age"><varname>vacuum_freeze_min_age</></link>
      transactions, this mistake prevented autovacuum from using partial-table
      scans, so that a full-table scan would always happen instead.
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent misbehavior when a <symbol>RowExpr</> or <symbol>XmlExpr</>
      is parse-analyzed twice (Andres Freund, Tom Lane)
     </para>

     <para>
      This mistake could be user-visible in contexts such as
      <literal>CREATE TABLE LIKE INCLUDING INDEXES</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Improve defenses against integer overflow in hashtable sizing
      calculations (Jeff Davis)
     </para>
    </listitem>

    <listitem>
     <para>
      Reject out-of-range dates in <function>to_date()</> (Hitoshi Harada)
     </para>
    </listitem>

    <listitem>
     <para>
      Ensure that non-ASCII prompt strings are translated to the correct
      code page on Windows (Alexander Law, Noah Misch)
     </para>

     <para>
      This bug affected <application>psql</> and some other client programs.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possible crash in <application>psql</>'s <command>\?</> command
      when not connected to a database (Meng Qingzhong)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>pg_upgrade</> to deal with invalid indexes safely
      (Bruce Momjian)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix one-byte buffer overrun in <application>libpq</>'s
      <function>PQprintTuples</> (Xi Wang)
     </para>

     <para>
      This ancient function is not used anywhere by
      <productname>PostgreSQL</> itself, but it might still be used by some
      client code.
     </para>
    </listitem>

    <listitem>
     <para>
      Make <application>ecpglib</> use translated messages properly
      (Chen Huajun)
     </para>
    </listitem>

    <listitem>
     <para>
      Properly install <application>ecpg_compat</> and
      <application>pgtypes</> libraries on MSVC (Jiang Guiqing)
     </para>
    </listitem>

    <listitem>
     <para>
      Include our version of <function>isinf()</> in
      <application>libecpg</> if it's not provided by the system
      (Jiang Guiqing)
     </para>
    </listitem>

    <listitem>
     <para>
      Rearrange configure's tests for supplied functions so it is not
      fooled by bogus exports from libedit/libreadline (Christoph Berg)
     </para>
    </listitem>

    <listitem>
     <para>
      Ensure Windows build number increases over time (Magnus Hagander)
     </para>
    </listitem>

    <listitem>
     <para>
      Make <application>pgxs</> build executables with the right
      <literal>.exe</> suffix when cross-compiling for Windows
      (Zoltan Boszormenyi)
     </para>
    </listitem>

    <listitem>
     <para>
      Add new timezone abbreviation <literal>FET</> (Tom Lane)
     </para>

     <para>
      This is now used in some eastern-European time zones.
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-9-0-11">
  <title>Release 9.0.11</title>

  <note>
  <title>Release Date</title>
  <simpara>2012-12-06</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 9.0.10.
   For information about new features in the 9.0 major release, see
   <xref linkend="release-9-0">.
  </para>

  <sect2>
   <title>Migration to Version 9.0.11</title>

   <para>
    A dump/restore is not required for those running 9.0.X.
   </para>

   <para>
    However, if you are upgrading from a version earlier than 9.0.6,
    see <xref linkend="release-9-0-6">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Fix multiple bugs associated with <command>CREATE INDEX
      CONCURRENTLY</> (Andres Freund, Tom Lane)
     </para>

     <para>
      Fix <command>CREATE INDEX CONCURRENTLY</> to use
      in-place updates when changing the state of an index's
      <structname>pg_index</> row.  This prevents race conditions that could
      cause concurrent sessions to miss updating the target index, thus
      resulting in corrupt concurrently-created indexes.
     </para>

     <para>
      Also, fix various other operations to ensure that they ignore
      invalid indexes resulting from a failed <command>CREATE INDEX
      CONCURRENTLY</> command.  The most important of these is
      <command>VACUUM</>, because an auto-vacuum could easily be launched
      on the table before corrective action can be taken to fix or remove
      the invalid index.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix buffer locking during WAL replay (Tom Lane)
     </para>

     <para>
      The WAL replay code was insufficiently careful about locking buffers
      when replaying WAL records that affect more than one page.  This could
      result in hot standby queries transiently seeing inconsistent states,
      resulting in wrong answers or unexpected failures.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix an error in WAL generation logic for GIN indexes (Tom Lane)
     </para>

     <para>
      This could result in index corruption, if a torn-page failure occurred.
     </para>
    </listitem>

    <listitem>
     <para>
      Properly remove startup process's virtual XID lock when promoting a
      hot standby server to normal running (Simon Riggs)
     </para>

     <para>
      This oversight could prevent subsequent execution of certain
      operations such as <command>CREATE INDEX CONCURRENTLY</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid bogus <quote>out-of-sequence timeline ID</> errors in standby
      mode (Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent the postmaster from launching new child processes after it's
      received a shutdown signal (Tom Lane)
     </para>

     <para>
      This mistake could result in shutdown taking longer than it should, or
      even never completing at all without additional user action.
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid corruption of internal hash tables when out of memory
      (Hitoshi Harada)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix planning of non-strict equivalence clauses above outer joins
      (Tom Lane)
     </para>

     <para>
      The planner could derive incorrect constraints from a clause equating
      a non-strict construct to something else, for example
      <literal>WHERE COALESCE(foo, 0) = 0</>
      when <literal>foo</> is coming from the nullable side of an outer join.
     </para>
    </listitem>

    <listitem>
     <para>
      Improve planner's ability to prove exclusion constraints from
      equivalence classes (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix partial-row matching in hashed subplans to handle cross-type cases
      correctly (Tom Lane)
     </para>

     <para>
      This affects multicolumn <literal>NOT IN</> subplans, such as
      <literal>WHERE (a, b) NOT IN (SELECT x, y FROM ...)</>
      when for instance <literal>b</> and <literal>y</> are <type>int4</>
      and <type>int8</> respectively.  This mistake led to wrong answers
      or crashes depending on the specific datatypes involved.
     </para>
    </listitem>

    <listitem>
     <para>
      Acquire buffer lock when re-fetching the old tuple for an
      <literal>AFTER ROW UPDATE/DELETE</> trigger (Andres Freund)
     </para>

     <para>
      In very unusual circumstances, this oversight could result in passing
      incorrect data to the precheck logic for a foreign-key enforcement
      trigger.  That could result in a crash, or in an incorrect decision
      about whether to fire the trigger.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <command>ALTER COLUMN TYPE</> to handle inherited check
      constraints properly (Pavan Deolasee)
     </para>

     <para>
      This worked correctly in pre-8.4 releases, and now works correctly
      in 8.4 and later.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <command>REASSIGN OWNED</> to handle grants on tablespaces
      (&Aacute;lvaro Herrera)
     </para>
    </listitem>

    <listitem>
     <para>
      Ignore incorrect <structname>pg_attribute</> entries for system
      columns for views (Tom Lane)
     </para>

     <para>
      Views do not have any system columns.  However, we forgot to
      remove such entries when converting a table to a view.  That's fixed
      properly for 9.3 and later, but in previous branches we need to defend
      against existing mis-converted views.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix rule printing to dump <literal>INSERT INTO <replaceable>table</>
      DEFAULT VALUES</literal> correctly (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Guard against stack overflow when there are too many
      <literal>UNION</>/<literal>INTERSECT</>/<literal>EXCEPT</> clauses
      in a query (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent platform-dependent failures when dividing the minimum possible
      integer value by -1 (Xi Wang, Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possible access past end of string in date parsing
      (Hitoshi Harada)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix failure to advance XID epoch if XID wraparound happens during a
      checkpoint and <varname>wal_level</> is <literal>hot_standby</>
      (Tom Lane, Andres Freund)
     </para>

     <para>
      While this mistake had no particular impact on
      <productname>PostgreSQL</productname> itself, it was bad for
      applications that rely on <function>txid_current()</> and related
      functions: the TXID value would appear to go backwards.
     </para>
    </listitem>

    <listitem>
     <para>
      Produce an understandable error message if the length of the path name
      for a Unix-domain socket exceeds the platform-specific limit
      (Tom Lane, Andrew Dunstan)
     </para>

     <para>
      Formerly, this would result in something quite unhelpful, such as
      <quote>Non-recoverable failure in name resolution</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix memory leaks when sending composite column values to the client
      (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Make <application>pg_ctl</> more robust about reading the
      <filename>postmaster.pid</> file (Heikki Linnakangas)
     </para>

     <para>
      Fix race conditions and possible file descriptor leakage.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possible crash in <application>psql</> if incorrectly-encoded data
      is presented and the <varname>client_encoding</> setting is a
      client-only encoding, such as SJIS (Jiang Guiqing)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix bugs in the <filename>restore.sql</> script emitted by
      <application>pg_dump</> in <literal>tar</> output format (Tom Lane)
     </para>

     <para>
      The script would fail outright on tables whose names include
      upper-case characters.  Also, make the script capable of restoring
      data in <option>--inserts</> mode as well as the regular COPY mode.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>pg_restore</> to accept POSIX-conformant
      <literal>tar</> files (Brian Weaver, Tom Lane)
     </para>

     <para>
      The original coding of <application>pg_dump</>'s <literal>tar</>
      output mode produced files that are not fully conformant with the
      POSIX standard.  This has been corrected for version 9.3.  This
      patch updates previous branches so that they will accept both the
      incorrect and the corrected formats, in hopes of avoiding
      compatibility problems when 9.3 comes out.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>pg_resetxlog</> to locate <filename>postmaster.pid</>
      correctly when given a relative path to the data directory (Tom Lane)
     </para>

     <para>
      This mistake could lead to <application>pg_resetxlog</> not noticing
      that there is an active postmaster using the data directory.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>libpq</>'s <function>lo_import()</> and
      <function>lo_export()</> functions to report file I/O errors properly
      (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>ecpg</>'s processing of nested structure pointer
      variables (Muhammad Usama)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>ecpg</>'s <function>ecpg_get_data</> function to
      handle arrays properly (Michael Meskes)
     </para>
    </listitem>

    <listitem>
     <para>
      Make <filename>contrib/pageinspect</>'s btree page inspection
      functions take buffer locks while examining pages (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>pgxs</> support for building loadable modules on AIX
      (Tom Lane)
     </para>

     <para>
      Building modules outside the original source tree didn't work on AIX.
     </para>
    </listitem>

    <listitem>
     <para>
      Update time zone data files to <application>tzdata</> release 2012j
      for DST law changes in Cuba, Israel, Jordan, Libya, Palestine, Western
      Samoa, and portions of Brazil.
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-9-0-10">
  <title>Release 9.0.10</title>

  <note>
  <title>Release Date</title>
  <simpara>2012-09-24</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 9.0.9.
   For information about new features in the 9.0 major release, see
   <xref linkend="release-9-0">.
  </para>

  <sect2>
   <title>Migration to Version 9.0.10</title>

   <para>
    A dump/restore is not required for those running 9.0.X.
   </para>

   <para>
    However, if you are upgrading from a version earlier than 9.0.6,
    see <xref linkend="release-9-0-6">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Fix planner's assignment of executor parameters, and fix executor's
      rescan logic for CTE plan nodes (Tom Lane)
     </para>

     <para>
      These errors could result in wrong answers from queries that scan the
      same <literal>WITH</> subquery multiple times.
     </para>
    </listitem>

    <listitem>
     <para>
      Improve page-splitting decisions in GiST indexes (Alexander Korotkov,
      Robert Haas, Tom Lane)
     </para>

     <para>
      Multi-column GiST indexes might suffer unexpected bloat due to this
      error.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix cascading privilege revoke to stop if privileges are still held
      (Tom Lane)
     </para>

     <para>
      If we revoke a grant option from some role <replaceable>X</>, but
      <replaceable>X</> still holds that option via a grant from someone
      else, we should not recursively revoke the corresponding privilege
      from role(s) <replaceable>Y</> that <replaceable>X</> had granted it
      to.
     </para>
    </listitem>

    <listitem>
     <para>
      Improve error messages for Hot Standby misconfiguration errors
      (Gurjeet Singh)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix handling of <literal>SIGFPE</> when PL/Perl is in use (Andres Freund)
     </para>

     <para>
      Perl resets the process's <literal>SIGFPE</> handler to
      <literal>SIG_IGN</>, which could result in crashes later on.  Restore
      the normal Postgres signal handler after initializing PL/Perl.
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent PL/Perl from crashing if a recursive PL/Perl function is
      redefined while being executed (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Work around possible misoptimization in PL/Perl (Tom Lane)
     </para>

     <para>
      Some Linux distributions contain an incorrect version of
      <filename>pthread.h</> that results in incorrect compiled code in
      PL/Perl, leading to crashes if a PL/Perl function calls another one
      that throws an error.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>pg_upgrade</>'s handling of line endings on Windows
      (Andrew Dunstan)
     </para>

     <para>
      Previously, <application>pg_upgrade</> might add or remove carriage
      returns in places such as function bodies.
     </para>
    </listitem>

    <listitem>
     <para>
      On Windows, make <application>pg_upgrade</> use backslash path
      separators in the scripts it emits (Andrew Dunstan)
     </para>
    </listitem>

    <listitem>
     <para>
      Update time zone data files to <application>tzdata</> release 2012f
      for DST law changes in Fiji
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-9-0-9">
  <title>Release 9.0.9</title>

  <note>
  <title>Release Date</title>
  <simpara>2012-08-17</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 9.0.8.
   For information about new features in the 9.0 major release, see
   <xref linkend="release-9-0">.
  </para>

  <sect2>
   <title>Migration to Version 9.0.9</title>

   <para>
    A dump/restore is not required for those running 9.0.X.
   </para>

   <para>
    However, if you are upgrading from a version earlier than 9.0.6,
    see <xref linkend="release-9-0-6">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Prevent access to external files/URLs via XML entity references
      (Noah Misch, Tom Lane)
     </para>

     <para>
      <function>xml_parse()</> would attempt to fetch external files or
      URLs as needed to resolve DTD and entity references in an XML value,
      thus allowing unprivileged database users to attempt to fetch data
      with the privileges of the database server.  While the external data
      wouldn't get returned directly to the user, portions of it could be
      exposed in error messages if the data didn't parse as valid XML; and
      in any case the mere ability to check existence of a file might be
      useful to an attacker.  (CVE-2012-3489)
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent access to external files/URLs via <filename>contrib/xml2</>'s
      <function>xslt_process()</> (Peter Eisentraut)
     </para>

     <para>
      <application>libxslt</> offers the ability to read and write both
      files and URLs through stylesheet commands, thus allowing
      unprivileged database users to both read and write data with the
      privileges of the database server.  Disable that through proper use
      of <application>libxslt</>'s security options.  (CVE-2012-3488)
     </para>

     <para>
      Also, remove <function>xslt_process()</>'s ability to fetch documents
      and stylesheets from external files/URLs.  While this was a
      documented <quote>feature</>, it was long regarded as a bad idea.
      The fix for CVE-2012-3489 broke that capability, and rather than
      expend effort on trying to fix it, we're just going to summarily
      remove it.
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent too-early recycling of btree index pages (Noah Misch)
     </para>

     <para>
      When we allowed read-only transactions to skip assigning XIDs, we
      introduced the possibility that a deleted btree page could be
      recycled while a read-only transaction was still in flight to it.
      This would result in incorrect index search results.  The probability
      of such an error occurring in the field seems very low because of the
      timing requirements, but nonetheless it should be fixed.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix crash-safety bug with newly-created-or-reset sequences (Tom Lane)
     </para>

     <para>
      If <command>ALTER SEQUENCE</> was executed on a freshly created or
      reset sequence, and then precisely one <function>nextval()</> call
      was made on it, and then the server crashed, WAL replay would restore
      the sequence to a state in which it appeared that no
      <function>nextval()</> had been done, thus allowing the first
      sequence value to be returned again by the next
      <function>nextval()</> call.  In particular this could manifest for
      <type>serial</> columns, since creation of a serial column's sequence
      includes an <command>ALTER SEQUENCE OWNED BY</> step.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <function>txid_current()</> to report the correct epoch when not
      in hot standby (Heikki Linnakangas)
     </para>

     <para>
      This fixes a regression introduced in the previous minor release.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix bug in startup of Hot Standby when a master transaction has many
      subtransactions (Andres Freund)
     </para>

     <para>
      This mistake led to failures reported as <quote>out-of-order XID
      insertion in KnownAssignedXids</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Ensure the <filename>backup_label</> file is fsync'd after
      <function>pg_start_backup()</> (Dave Kerr)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix timeout handling in walsender processes (Tom Lane)
     </para>

     <para>
      WAL sender background processes neglected to establish a
      <systemitem>SIGALRM</> handler, meaning they would wait forever in
      some corner cases where a timeout ought to happen.
     </para>
    </listitem>

    <listitem>
     <para>
      Back-patch 9.1 improvement to compress the fsync request queue
      (Robert Haas)
     </para>

     <para>
      This improves performance during checkpoints.  The 9.1 change
      has now seen enough field testing to seem safe to back-patch.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <literal>LISTEN</>/<literal>NOTIFY</> to cope better with I/O
      problems, such as out of disk space (Tom Lane)
     </para>

     <para>
      After a write failure, all subsequent attempts to send more
      <literal>NOTIFY</> messages would fail with messages like
      <quote>Could not read from file "pg_notify/<replaceable>nnnn</>" at
      offset <replaceable>nnnnn</>: Success</quote>.
     </para>
    </listitem>

    <listitem>
     <para>
      Only allow autovacuum to be auto-canceled by a directly blocked
      process (Tom Lane)
     </para>

     <para>
      The original coding could allow inconsistent behavior in some cases;
      in particular, an autovacuum could get canceled after less than
      <literal>deadlock_timeout</> grace period.
     </para>
    </listitem>

    <listitem>
     <para>
      Improve logging of autovacuum cancels (Robert Haas)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix log collector so that <literal>log_truncate_on_rotation</> works
      during the very first log rotation after server start (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <literal>WITH</> attached to a nested set operation
      (<literal>UNION</>/<literal>INTERSECT</>/<literal>EXCEPT</>)
      (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Ensure that a whole-row reference to a subquery doesn't include any
      extra <literal>GROUP BY</> or <literal>ORDER BY</> columns (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Disallow copying whole-row references in <literal>CHECK</>
      constraints and index definitions during <command>CREATE TABLE</>
      (Tom Lane)
     </para>

     <para>
      This situation can arise in <command>CREATE TABLE</> with
      <literal>LIKE</> or <literal>INHERITS</>.  The copied whole-row
      variable was incorrectly labeled with the row type of the original
      table not the new one.  Rejecting the case seems reasonable for
      <literal>LIKE</>, since the row types might well diverge later.  For
      <literal>INHERITS</> we should ideally allow it, with an implicit
      coercion to the parent table's row type; but that will require more
      work than seems safe to back-patch.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix memory leak in <literal>ARRAY(SELECT ...)</> subqueries (Heikki
      Linnakangas, Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix extraction of common prefixes from regular expressions (Tom Lane)
     </para>

     <para>
      The code could get confused by quantified parenthesized
      subexpressions, such as <literal>^(foo)?bar</>.  This would lead to
      incorrect index optimization of searches for such patterns.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix bugs with parsing signed
      <replaceable>hh</><literal>:</><replaceable>mm</> and
      <replaceable>hh</><literal>:</><replaceable>mm</><literal>:</><replaceable>ss</>
      fields in <type>interval</> constants (Amit Kapila, Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Use Postgres' encoding conversion functions, not Python's, when
      converting a Python Unicode string to the server encoding in
      PL/Python (Jan Urbanski)
     </para>

     <para>
      This avoids some corner-case problems, notably that Python doesn't
      support all the encodings Postgres does.  A notable functional change
      is that if the server encoding is SQL_ASCII, you will get the UTF-8
      representation of the string; formerly, any non-ASCII characters in
      the string would result in an error.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix mapping of PostgreSQL encodings to Python encodings in PL/Python
      (Jan Urbanski)
     </para>
    </listitem>

    <listitem>
     <para>
      Report errors properly in <filename>contrib/xml2</>'s
      <function>xslt_process()</> (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Update time zone data files to <application>tzdata</> release 2012e
      for DST law changes in Morocco and Tokelau
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-9-0-8">
  <title>Release 9.0.8</title>

  <note>
  <title>Release Date</title>
  <simpara>2012-06-04</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 9.0.7.
   For information about new features in the 9.0 major release, see
   <xref linkend="release-9-0">.
  </para>

  <sect2>
   <title>Migration to Version 9.0.8</title>

   <para>
    A dump/restore is not required for those running 9.0.X.
   </para>

   <para>
    However, if you are upgrading from a version earlier than 9.0.6,
    see <xref linkend="release-9-0-6">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Fix incorrect password transformation in
      <filename>contrib/pgcrypto</>'s DES <function>crypt()</> function
      (Solar Designer)
     </para>

     <para>
      If a password string contained the byte value <literal>0x80</>, the
      remainder of the password was ignored, causing the password to be much
      weaker than it appeared.  With this fix, the rest of the string is
      properly included in the DES hash.  Any stored password values that are
      affected by this bug will thus no longer match, so the stored values may
      need to be updated.  (CVE-2012-2143)
     </para>
    </listitem>

    <listitem>
     <para>
      Ignore <literal>SECURITY DEFINER</> and <literal>SET</> attributes for
      a procedural language's call handler (Tom Lane)
     </para>

     <para>
      Applying such attributes to a call handler could crash the server.
      (CVE-2012-2655)
     </para>
    </listitem>

    <listitem>
     <para>
      Allow numeric timezone offsets in <type>timestamp</> input to be up to
      16 hours away from UTC (Tom Lane)
     </para>

     <para>
      Some historical time zones have offsets larger than 15 hours, the
      previous limit.  This could result in dumped data values being rejected
      during reload.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix timestamp conversion to cope when the given time is exactly the
      last DST transition time for the current timezone (Tom Lane)
     </para>

     <para>
      This oversight has been there a long time, but was not noticed
      previously because most DST-using zones are presumed to have an
      indefinite sequence of future DST transitions.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <type>text</> to <type>name</> and <type>char</> to <type>name</>
      casts to perform string truncation correctly in multibyte encodings
      (Karl Schnaitter)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix memory copying bug in <function>to_tsquery()</> (Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      Ensure <function>txid_current()</> reports the correct epoch when
      executed in hot standby (Simon Riggs)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix planner's handling of outer PlaceHolderVars within subqueries (Tom
      Lane)
     </para>

     <para>
      This bug concerns sub-SELECTs that reference variables coming from the
      nullable side of an outer join of the surrounding query.
      In 9.1, queries affected by this bug would fail with <quote>ERROR:
      Upper-level PlaceHolderVar found where not expected</>.  But in 9.0 and
      8.4, you'd silently get possibly-wrong answers, since the value
      transmitted into the subquery wouldn't go to null when it should.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix slow session startup when <structname>pg_attribute</> is very large
      (Tom Lane)
     </para>

     <para>
      If <structname>pg_attribute</> exceeds one-fourth of
      <varname>shared_buffers</>, cache rebuilding code that is sometimes
      needed during session start would trigger the synchronized-scan logic,
      causing it to take many times longer than normal.  The problem was
      particularly acute if many new sessions were starting at once.
     </para>
    </listitem>

    <listitem>
     <para>
      Ensure sequential scans check for query cancel reasonably often (Merlin
      Moncure)
     </para>

     <para>
      A scan encountering many consecutive pages that contain no live tuples
      would not respond to interrupts meanwhile.
     </para>
    </listitem>

    <listitem>
     <para>
      Ensure the Windows implementation of <function>PGSemaphoreLock()</>
      clears <varname>ImmediateInterruptOK</> before returning (Tom Lane)
     </para>

     <para>
      This oversight meant that a query-cancel interrupt received later
      in the same query could be accepted at an unsafe time, with
      unpredictable but not good consequences.
     </para>
    </listitem>

    <listitem>
     <para>
      Show whole-row variables safely when printing views or rules
      (Abbas Butt, Tom Lane)
     </para>

     <para>
      Corner cases involving ambiguous names (that is, the name could be
      either a table or column name of the query) were printed in an
      ambiguous way, risking that the view or rule would be interpreted
      differently after dump and reload.  Avoid the ambiguous case by
      attaching a no-op cast.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <command>COPY FROM</> to properly handle null marker strings that
      correspond to invalid encoding (Tom Lane)
     </para>

     <para>
      A null marker string such as <literal>E'\\0'</> should work, and did
      work in the past, but the case got broken in 8.4.
     </para>
    </listitem>

    <listitem>
     <para>
      Ensure autovacuum worker processes perform stack depth checking
      properly (Heikki Linnakangas)
     </para>

     <para>
      Previously, infinite recursion in a function invoked by
      auto-<command>ANALYZE</> could crash worker processes.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix logging collector to not lose log coherency under high load (Andrew
      Dunstan)
     </para>

     <para>
      The collector previously could fail to reassemble large messages if it
      got too busy.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix logging collector to ensure it will restart file rotation
      after receiving <systemitem>SIGHUP</> (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix WAL replay logic for GIN indexes to not fail if the index was
      subsequently dropped (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix memory leak in PL/pgSQL's <command>RETURN NEXT</> command (Joe
      Conway)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix PL/pgSQL's <command>GET DIAGNOSTICS</> command when the target
      is the function's first variable (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix potential access off the end of memory in <application>psql</>'s
      expanded display (<command>\x</>) mode (Peter Eisentraut)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix several performance problems in <application>pg_dump</> when
      the database contains many objects (Jeff Janes, Tom Lane)
     </para>

     <para>
      <application>pg_dump</> could get very slow if the database contained
      many schemas, or if many objects are in dependency loops, or if there
      are many owned sequences.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>pg_upgrade</> for the case that a database stored in a
      non-default tablespace contains a table in the cluster's default
      tablespace (Bruce Momjian)
     </para>
    </listitem>

    <listitem>
     <para>
      In <application>ecpg</>, fix rare memory leaks and possible overwrite
      of one byte after the <structname>sqlca_t</> structure (Peter Eisentraut)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <filename>contrib/dblink</>'s <function>dblink_exec()</> to not leak
      temporary database connections upon error (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <filename>contrib/dblink</> to report the correct connection name in
      error messages (Kyotaro Horiguchi)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <filename>contrib/vacuumlo</> to use multiple transactions when
      dropping many large objects (Tim Lewis, Robert Haas, Tom Lane)
     </para>

     <para>
      This change avoids exceeding <varname>max_locks_per_transaction</> when
      many objects need to be dropped.  The behavior can be adjusted with the
      new <literal>-l</> (limit) option.
     </para>
    </listitem>

    <listitem>
     <para>
      Update time zone data files to <application>tzdata</> release 2012c
      for DST law changes in Antarctica, Armenia, Chile, Cuba, Falkland
      Islands, Gaza, Haiti, Hebron, Morocco, Syria, and Tokelau Islands;
      also historical corrections for Canada.
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-9-0-7">
  <title>Release 9.0.7</title>

  <note>
  <title>Release Date</title>
  <simpara>2012-02-27</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 9.0.6.
   For information about new features in the 9.0 major release, see
   <xref linkend="release-9-0">.
  </para>

  <sect2>
   <title>Migration to Version 9.0.7</title>

   <para>
    A dump/restore is not required for those running 9.0.X.
   </para>

   <para>
    However, if you are upgrading from a version earlier than 9.0.6,
    see <xref linkend="release-9-0-6">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Require execute permission on the trigger function for
      <command>CREATE TRIGGER</> (Robert Haas)
     </para>

     <para>
      This missing check could allow another user to execute a trigger
      function with forged input data, by installing it on a table he owns.
      This is only of significance for trigger functions marked
      <literal>SECURITY DEFINER</>, since otherwise trigger functions run
      as the table owner anyway.  (CVE-2012-0866)
     </para>
    </listitem>

    <listitem>
     <para>
      Remove arbitrary limitation on length of common name in SSL
      certificates (Heikki Linnakangas)
     </para>

     <para>
      Both <application>libpq</> and the server truncated the common name
      extracted from an SSL certificate at 32 bytes.  Normally this would
      cause nothing worse than an unexpected verification failure, but there
      are some rather-implausible scenarios in which it might allow one
      certificate holder to impersonate another.  The victim would have to
      have a common name exactly 32 bytes long, and the attacker would have
      to persuade a trusted CA to issue a certificate in which the common
      name has that string as a prefix.  Impersonating a server would also
      require some additional exploit to redirect client connections.
      (CVE-2012-0867)
     </para>
    </listitem>

    <listitem>
     <para>
      Convert newlines to spaces in names written in <application>pg_dump</>
      comments (Robert Haas)
     </para>

     <para>
      <application>pg_dump</> was incautious about sanitizing object names
      that are emitted within SQL comments in its output script.  A name
      containing a newline would at least render the script syntactically
      incorrect.  Maliciously crafted object names could present a SQL
      injection risk when the script is reloaded.  (CVE-2012-0868)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix btree index corruption from insertions concurrent with vacuuming
      (Tom Lane)
     </para>

     <para>
      An index page split caused by an insertion could sometimes cause a
      concurrently-running <command>VACUUM</> to miss removing index entries
      that it should remove.  After the corresponding table rows are removed,
      the dangling index entries would cause errors (such as <quote>could not
      read block N in file ...</>) or worse, silently wrong query results
      after unrelated rows are re-inserted at the now-free table locations.
      This bug has been present since release 8.2, but occurs so infrequently
      that it was not diagnosed until now.  If you have reason to suspect
      that it has happened in your database, reindexing the affected index
      will fix things.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix transient zeroing of shared buffers during WAL replay (Tom Lane)
     </para>

     <para>
      The replay logic would sometimes zero and refill a shared buffer, so
      that the contents were transiently invalid.  In hot standby mode this
      can result in a query that's executing in parallel seeing garbage data.
      Various symptoms could result from that, but the most common one seems
      to be <quote>invalid memory alloc request size</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix postmaster to attempt restart after a hot-standby crash (Tom Lane)
     </para>

     <para>
      A logic error caused the postmaster to terminate, rather than attempt
      to restart the cluster, if any backend process crashed while operating
      in hot standby mode.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <command>CLUSTER</>/<command>VACUUM FULL</> handling of toast
      values owned by recently-updated rows (Tom Lane)
     </para>

     <para>
      This oversight could lead to <quote>duplicate key value violates unique
      constraint</> errors being reported against the toast table's index
      during one of these commands.
     </para>
    </listitem>

    <listitem>
     <para>
      Update per-column permissions, not only per-table permissions, when
      changing table owner (Tom Lane)
     </para>

     <para>
      Failure to do this meant that any previously granted column permissions
      were still shown as having been granted by the old owner.  This meant
      that neither the new owner nor a superuser could revoke the
      now-untraceable-to-table-owner permissions.
     </para>
    </listitem>

    <listitem>
     <para>
      Support foreign data wrappers and foreign servers in
      <command>REASSIGN OWNED</> (Alvaro Herrera)
     </para>

     <para>
      This command failed with <quote>unexpected classid</> errors if
      it needed to change the ownership of any such objects.
     </para>
    </listitem>

    <listitem>
     <para>
      Allow non-existent values for some settings in <command>ALTER
      USER/DATABASE SET</> (Heikki Linnakangas)
     </para>

     <para>
      Allow <varname>default_text_search_config</>,
      <varname>default_tablespace</>, and <varname>temp_tablespaces</> to be
      set to names that are not known.  This is because they might be known
      in another database where the setting is intended to be used, or for the
      tablespace cases because the tablespace might not be created yet.  The
      same issue was previously recognized for <varname>search_path</>, and
      these settings now act like that one.
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid crashing when we have problems deleting table files post-commit
      (Tom Lane)
     </para>

     <para>
      Dropping a table should lead to deleting the underlying disk files only
      after the transaction commits.  In event of failure then (for instance,
      because of wrong file permissions) the code is supposed to just emit a
      warning message and go on, since it's too late to abort the
      transaction.  This logic got broken as of release 8.4, causing such
      situations to result in a PANIC and an unrestartable database.
     </para>
    </listitem>

    <listitem>
     <para>
      Recover from errors occurring during WAL replay of <command>DROP
      TABLESPACE</> (Tom Lane)
     </para>

     <para>
      Replay will attempt to remove the tablespace's directories, but there
      are various reasons why this might fail (for example, incorrect
      ownership or permissions on those directories).  Formerly the replay
      code would panic, rendering the database unrestartable without manual
      intervention.  It seems better to log the problem and continue, since
      the only consequence of failure to remove the directories is some
      wasted disk space.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix race condition in logging AccessExclusiveLocks for hot standby
      (Simon Riggs)
     </para>

     <para>
      Sometimes a lock would be logged as being held by <quote>transaction
      zero</>.  This is at least known to produce assertion failures on
      slave servers, and might be the cause of more serious problems.
     </para>
    </listitem>

    <listitem>
     <para>
      Track the OID counter correctly during WAL replay, even when it wraps
      around (Tom Lane)
     </para>

     <para>
      Previously the OID counter would remain stuck at a high value until the
      system exited replay mode.  The practical consequences of that are
      usually nil, but there are scenarios wherein a standby server that's
      been promoted to master might take a long time to advance the OID
      counter to a reasonable value once values are needed.
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent emitting misleading <quote>consistent recovery state reached</>
      log message at the beginning of crash recovery (Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix initial value of
      <structname>pg_stat_replication</>.<structfield>replay_location</>
      (Fujii Masao)
     </para>

     <para>
      Previously, the value shown would be wrong until at least one WAL
      record had been replayed.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix regular expression back-references with <literal>*</> attached
      (Tom Lane)
     </para>

     <para>
      Rather than enforcing an exact string match, the code would effectively
      accept any string that satisfies the pattern sub-expression referenced
      by the back-reference symbol.
     </para>

     <para>
      A similar problem still afflicts back-references that are embedded in a
      larger quantified expression, rather than being the immediate subject
      of the quantifier.  This will be addressed in a future
      <productname>PostgreSQL</> release.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix recently-introduced memory leak in processing of
      <type>inet</>/<type>cidr</> values (Heikki Linnakangas)
     </para>

     <para>
      A patch in the December 2011 releases of <productname>PostgreSQL</>
      caused memory leakage in these operations, which could be significant
      in scenarios such as building a btree index on such a column.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix dangling pointer after <command>CREATE TABLE AS</>/<command>SELECT
      INTO</> in a SQL-language function (Tom Lane)
     </para>

     <para>
      In most cases this only led to an assertion failure in assert-enabled
      builds, but worse consequences seem possible.
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid double close of file handle in syslogger on Windows (MauMau)
     </para>

     <para>
      Ordinarily this error was invisible, but it would cause an exception
      when running on a debug version of Windows.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix I/O-conversion-related memory leaks in plpgsql
      (Andres Freund, Jan Urbanski, Tom Lane)
     </para>

     <para>
      Certain operations would leak memory until the end of the current
      function.
     </para>
    </listitem>

    <listitem>
     <para>
      Improve <application>pg_dump</>'s handling of inherited table columns
      (Tom Lane)
     </para>

     <para>
      <application>pg_dump</> mishandled situations where a child column has
      a different default expression than its parent column.  If the default
      is textually identical to the parent's default, but not actually the
      same (for instance, because of schema search path differences) it would
      not be recognized as different, so that after dump and restore the
      child would be allowed to inherit the parent's default.  Child columns
      that are <literal>NOT NULL</> where their parent is not could also be
      restored subtly incorrectly.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>pg_restore</>'s direct-to-database mode for
      INSERT-style table data (Tom Lane)
     </para>

     <para>
      Direct-to-database restores from archive files made with
      <option>--inserts</> or <option>--column-inserts</> options fail when
      using <application>pg_restore</> from a release dated September or
      December 2011, as a result of an oversight in a fix for another
      problem.  The archive file itself is not at fault, and text-mode
      output is okay.
     </para>
    </listitem>

    <listitem>
     <para>
      Allow <application>pg_upgrade</> to process tables containing
      <type>regclass</> columns (Bruce Momjian)
     </para>

     <para>
      Since <application>pg_upgrade</> now takes care to preserve
      <structname>pg_class</> OIDs, there was no longer any reason for this
      restriction.
     </para>
    </listitem>

    <listitem>
     <para>
      Make <application>libpq</> ignore <literal>ENOTDIR</> errors
      when looking for an SSL client certificate file
      (Magnus Hagander)
     </para>

     <para>
      This allows SSL connections to be established, though without a
      certificate, even when the user's home directory is set to something
      like <literal>/dev/null</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix some more field alignment issues in <application>ecpg</>'s SQLDA area
      (Zoltan Boszormenyi)
     </para>
    </listitem>

    <listitem>
     <para>
      Allow <literal>AT</> option in <application>ecpg</>
      <literal>DEALLOCATE</> statements (Michael Meskes)
     </para>

     <para>
      The infrastructure to support this has been there for awhile, but
      through an oversight there was still an error check rejecting the case.
     </para>
    </listitem>

    <listitem>
     <para>
      Do not use the variable name when defining a varchar structure in ecpg
      (Michael Meskes)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <filename>contrib/auto_explain</>'s JSON output mode to produce
      valid JSON (Andrew Dunstan)
     </para>

     <para>
      The output used brackets at the top level, when it should have used
      braces.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix error in <filename>contrib/intarray</>'s <literal>int[] &amp;
      int[]</> operator (Guillaume Lelarge)
     </para>

     <para>
      If the smallest integer the two input arrays have in common is 1,
      and there are smaller values in either array, then 1 would be
      incorrectly omitted from the result.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix error detection in <filename>contrib/pgcrypto</>'s
      <function>encrypt_iv()</> and <function>decrypt_iv()</>
      (Marko Kreen)
     </para>

     <para>
      These functions failed to report certain types of invalid-input errors,
      and would instead return random garbage values for incorrect input.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix one-byte buffer overrun in <filename>contrib/test_parser</>
      (Paul Guyot)
     </para>

     <para>
      The code would try to read one more byte than it should, which would
      crash in corner cases.
      Since <filename>contrib/test_parser</> is only example code, this is
      not a security issue in itself, but bad example code is still bad.
     </para>
    </listitem>

    <listitem>
     <para>
      Use <function>__sync_lock_test_and_set()</> for spinlocks on ARM, if
      available (Martin Pitt)
     </para>

     <para>
      This function replaces our previous use of the <literal>SWPB</>
      instruction, which is deprecated and not available on ARMv6 and later.
      Reports suggest that the old code doesn't fail in an obvious way on
      recent ARM boards, but simply doesn't interlock concurrent accesses,
      leading to bizarre failures in multiprocess operation.
     </para>
    </listitem>

    <listitem>
     <para>
      Use <option>-fexcess-precision=standard</> option when building with
      gcc versions that accept it (Andrew Dunstan)
     </para>

     <para>
      This prevents assorted scenarios wherein recent versions of gcc will
      produce creative results.
     </para>
    </listitem>

    <listitem>
     <para>
      Allow use of threaded Python on FreeBSD (Chris Rees)
     </para>

     <para>
      Our configure script previously believed that this combination wouldn't
      work; but FreeBSD fixed the problem, so remove that error check.
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-9-0-6">
  <title>Release 9.0.6</title>

  <note>
  <title>Release Date</title>
  <simpara>2011-12-05</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 9.0.5.
   For information about new features in the 9.0 major release, see
   <xref linkend="release-9-0">.
  </para>

  <sect2>
   <title>Migration to Version 9.0.6</title>

   <para>
    A dump/restore is not required for those running 9.0.X.
   </para>

   <para>
    However, a longstanding error was discovered in the definition of the
    <literal>information_schema.referential_constraints</> view.  If you
    rely on correct results from that view, you should replace its
    definition as explained in the first changelog item below.
   </para>

   <para>
    Also, if you are upgrading from a version earlier than 9.0.4,
    see <xref linkend="release-9-0-4">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Fix bugs in <literal>information_schema.referential_constraints</> view
      (Tom Lane)
     </para>

     <para>
      This view was being insufficiently careful about matching the
      foreign-key constraint to the depended-on primary or unique key
      constraint.  That could result in failure to show a foreign key
      constraint at all, or showing it multiple times, or claiming that it
      depends on a different constraint than the one it really does.
     </para>

     <para>
      Since the view definition is installed by <application>initdb</>,
      merely upgrading will not fix the problem.  If you need to fix this
      in an existing installation, you can (as a superuser) drop the
      <literal>information_schema</> schema then re-create it by sourcing
      <filename><replaceable>SHAREDIR</>/information_schema.sql</filename>.
      (Run <literal>pg_config --sharedir</> if you're uncertain where
      <replaceable>SHAREDIR</> is.)  This must be repeated in each database
      to be fixed.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possible crash during <command>UPDATE</> or <command>DELETE</> that
      joins to the output of a scalar-returning function (Tom Lane)
     </para>

     <para>
      A crash could only occur if the target row had been concurrently
      updated, so this problem surfaced only intermittently.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix incorrect replay of WAL records for GIN index updates
      (Tom Lane)
     </para>

     <para>
      This could result in transiently failing to find index entries after
      a crash, or on a hot-standby server.  The problem would be repaired
      by the next <command>VACUUM</> of the index, however.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix TOAST-related data corruption during <literal>CREATE TABLE dest AS
      SELECT * FROM src</> or <literal>INSERT INTO dest SELECT * FROM src</>
      (Tom Lane)
     </para>

     <para>
      If a table has been modified by <command>ALTER TABLE ADD COLUMN</>,
      attempts to copy its data verbatim to another table could produce
      corrupt results in certain corner cases.
      The problem can only manifest in this precise form in 8.4 and later,
      but we patched earlier versions as well in case there are other code
      paths that could trigger the same bug.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possible failures during hot standby startup (Simon Riggs)
     </para>
    </listitem>

    <listitem>
     <para>
      Start hot standby faster when initial snapshot is incomplete
      (Simon Riggs)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix race condition during toast table access from stale syscache entries
      (Tom Lane)
     </para>

     <para>
      The typical symptom was transient errors like <quote>missing chunk
      number 0 for toast value NNNNN in pg_toast_2619</>, where the cited
      toast table would always belong to a system catalog.
     </para>
    </listitem>

    <listitem>
     <para>
      Track dependencies of functions on items used in parameter default
      expressions (Tom Lane)
     </para>

     <para>
      Previously, a referenced object could be dropped without having dropped
      or modified the function, leading to misbehavior when the function was
      used.  Note that merely installing this update will not fix the missing
      dependency entries; to do that, you'd need to <command>CREATE OR
      REPLACE</> each such function afterwards.  If you have functions whose
      defaults depend on non-built-in objects, doing so is recommended.
     </para>
    </listitem>

    <listitem>
     <para>
      Allow inlining of set-returning SQL functions with multiple OUT
      parameters (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Don't trust deferred-unique indexes for join removal (Tom Lane and Marti
      Raudsepp)
     </para>

     <para>
      A deferred uniqueness constraint might not hold intra-transaction,
      so assuming that it does could give incorrect query results.
     </para>
    </listitem>

    <listitem>
     <para>
      Make <function>DatumGetInetP()</> unpack inet datums that have a 1-byte
      header, and add a new macro, <function>DatumGetInetPP()</>, that does
      not (Heikki Linnakangas)
     </para>

     <para>
      This change affects no core code, but might prevent crashes in add-on
      code that expects <function>DatumGetInetP()</> to produce an unpacked
      datum as per usual convention.
     </para>
    </listitem>

    <listitem>
     <para>
      Improve locale support in <type>money</> type's input and output
      (Tom Lane)
     </para>

     <para>
      Aside from not supporting all standard
      <link linkend="guc-lc-monetary"><varname>lc_monetary</></link>
      formatting options, the input and output functions were inconsistent,
      meaning there were locales in which dumped <type>money</> values could
      not be re-read.
     </para>
    </listitem>

    <listitem>
     <para>
      Don't let <link
      linkend="guc-transform-null-equals"><varname>transform_null_equals</></link>
      affect <literal>CASE foo WHEN NULL ...</> constructs
      (Heikki Linnakangas)
     </para>

     <para>
      <varname>transform_null_equals</> is only supposed to affect
      <literal>foo = NULL</> expressions written directly by the user, not
      equality checks generated internally by this form of <literal>CASE</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Change foreign-key trigger creation order to better support
      self-referential foreign keys (Tom Lane)
     </para>

     <para>
      For a cascading foreign key that references its own table, a row update
      will fire both the <literal>ON UPDATE</> trigger and the
      <literal>CHECK</> trigger as one event.  The <literal>ON UPDATE</>
      trigger must execute first, else the <literal>CHECK</> will check a
      non-final state of the row and possibly throw an inappropriate error.
      However, the firing order of these triggers is determined by their
      names, which generally sort in creation order since the triggers have
      auto-generated names following the convention
      <quote>RI_ConstraintTrigger_NNNN</>.  A proper fix would require
      modifying that convention, which we will do in 9.2, but it seems risky
      to change it in existing releases.  So this patch just changes the
      creation order of the triggers.  Users encountering this type of error
      should drop and re-create the foreign key constraint to get its
      triggers into the right order.
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid floating-point underflow while tracking buffer allocation rate
      (Greg Matthews)
     </para>

     <para>
      While harmless in itself, on certain platforms this would result in
      annoying kernel log messages.
     </para>
    </listitem>

    <listitem>
     <para>
      Preserve configuration file name and line number values when starting
      child processes under Windows (Tom Lane)
     </para>

     <para>
      Formerly, these would not be displayed correctly in the
      <structname>pg_settings</> view.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix incorrect field alignment in <application>ecpg</>'s SQLDA area
      (Zoltan Boszormenyi)
     </para>
    </listitem>

    <listitem>
     <para>
      Preserve blank lines within commands in <application>psql</>'s command
      history (Robert Haas)
     </para>

     <para>
      The former behavior could cause problems if an empty line was removed
      from within a string literal, for example.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>pg_dump</> to dump user-defined casts between
      auto-generated types, such as table rowtypes (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Assorted fixes for <application>pg_upgrade</> (Bruce Momjian)
     </para>

     <para>
      Handle exclusion constraints correctly, avoid failures on Windows,
      don't complain about mismatched toast table names in 8.4 databases.
     </para>
    </listitem>

    <listitem>
     <para>
      Use the preferred version of <application>xsubpp</> to build PL/Perl,
      not necessarily the operating system's main copy
      (David Wheeler and Alex Hunsaker)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix incorrect coding in <filename>contrib/dict_int</> and
      <filename>contrib/dict_xsyn</> (Tom Lane)
     </para>

     <para>
      Some functions incorrectly assumed that memory returned by
      <function>palloc()</> is guaranteed zeroed.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix assorted errors in <filename>contrib/unaccent</>'s configuration
      file parsing (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Honor query cancel interrupts promptly in <function>pgstatindex()</>
      (Robert Haas)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix incorrect quoting of log file name in Mac OS X start script
      (Sidar Lopez)
     </para>
    </listitem>

    <listitem>
     <para>
      Ensure VPATH builds properly install all server header files
      (Peter Eisentraut)
     </para>
    </listitem>

    <listitem>
     <para>
      Shorten file names reported in verbose error messages (Peter Eisentraut)
     </para>

     <para>
      Regular builds have always reported just the name of the C file
      containing the error message call, but VPATH builds formerly
      reported an absolute path name.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix interpretation of Windows timezone names for Central America
      (Tom Lane)
     </para>

     <para>
      Map <quote>Central America Standard Time</> to <literal>CST6</>, not
      <literal>CST6CDT</>, because DST is generally not observed anywhere in
      Central America.
     </para>
    </listitem>

    <listitem>
     <para>
      Update time zone data files to <application>tzdata</> release 2011n
      for DST law changes in Brazil, Cuba, Fiji, Palestine, Russia, and Samoa;
      also historical corrections for Alaska and British East Africa.
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-9-0-5">
  <title>Release 9.0.5</title>

  <note>
  <title>Release Date</title>
  <simpara>2011-09-26</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 9.0.4.
   For information about new features in the 9.0 major release, see
   <xref linkend="release-9-0">.
  </para>

  <sect2>
   <title>Migration to Version 9.0.5</title>

   <para>
    A dump/restore is not required for those running 9.0.X.
   </para>

   <para>
    However, if you are upgrading from a version earlier than 9.0.4,
    see <xref linkend="release-9-0-4">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Fix catalog cache invalidation after a <command>VACUUM FULL</> or
      <command>CLUSTER</> on a system catalog (Tom Lane)
     </para>

     <para>
      In some cases the relocation of a system catalog row to another place
      would not be recognized by concurrent server processes, allowing catalog
      corruption to occur if they then tried to update that row.  The
      worst-case outcome could be as bad as complete loss of a table.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix incorrect order of operations during sinval reset processing,
      and ensure that TOAST OIDs are preserved in system catalogs (Tom
      Lane)
     </para>

     <para>
      These mistakes could lead to transient failures after a <command>VACUUM
      FULL</> or <command>CLUSTER</> on a system catalog.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix bugs in indexing of in-doubt HOT-updated tuples (Tom Lane)
     </para>

     <para>
      These bugs could result in index corruption after reindexing a system
      catalog.  They are not believed to affect user indexes.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix multiple bugs in GiST index page split processing (Heikki
      Linnakangas)
     </para>

     <para>
      The probability of occurrence was low, but these could lead to index
      corruption.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possible buffer overrun in <function>tsvector_concat()</>
      (Tom Lane)
     </para>

     <para>
      The function could underestimate the amount of memory needed for its
      result, leading to server crashes.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix crash in <function>xml_recv</> when processing a
      <quote>standalone</> parameter (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Make <function>pg_options_to_table</> return NULL for an option with no
      value (Tom Lane)
     </para>

     <para>
      Previously such cases would result in a server crash.
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid possibly accessing off the end of memory in <command>ANALYZE</>
      and in SJIS-2004 encoding conversion (Noah Misch)
     </para>

     <para>
      This fixes some very-low-probability server crash scenarios.
     </para>
    </listitem>

    <listitem>
     <para>
      Protect <function>pg_stat_reset_shared()</> against NULL input (Magnus
      Hagander)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possible failure when a recovery conflict deadlock is detected
      within a sub-transaction (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid spurious conflicts while recycling btree index pages during hot
      standby (Noah Misch, Simon Riggs)
     </para>
    </listitem>

    <listitem>
     <para>
      Shut down WAL receiver if it's still running at end of recovery (Heikki
      Linnakangas)
     </para>

     <para>
      The postmaster formerly panicked in this situation, but it's actually a
      legitimate case.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix race condition in relcache init file invalidation (Tom Lane)
     </para>

     <para>
      There was a window wherein a new backend process could read a stale init
      file but miss the inval messages that would tell it the data is stale.
      The result would be bizarre failures in catalog accesses, typically
      <quote>could not read block 0 in file ...</> later during startup.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix memory leak at end of a GiST index scan (Tom Lane)
     </para>

     <para>
      Commands that perform many separate GiST index scans, such as
      verification of a new GiST-based exclusion constraint on a table
      already containing many rows, could transiently require large amounts of
      memory due to this leak.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix memory leak when encoding conversion has to be done on incoming
      command strings and <command>LISTEN</> is active (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix incorrect memory accounting (leading to possible memory bloat) in
      tuplestores supporting holdable cursors and plpgsql's <literal>RETURN
      NEXT</> command (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix trigger <literal>WHEN</> conditions when both <literal>BEFORE</> and
      <literal>AFTER</> triggers exist (Tom Lane)
     </para>

     <para>
      Evaluation of <literal>WHEN</> conditions for <literal>AFTER ROW
      UPDATE</> triggers could crash if there had been a <literal>BEFORE
      ROW</> trigger fired for the same update.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix performance problem when constructing a large, lossy bitmap
      (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix join selectivity estimation for unique columns (Tom Lane)
     </para>

     <para>
      This fixes an erroneous planner heuristic that could lead to poor
      estimates of the result size of a join.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix nested PlaceHolderVar expressions that appear only in sub-select
      target lists (Tom Lane)
     </para>

     <para>
      This mistake could result in outputs of an outer join incorrectly
      appearing as NULL.
     </para>
    </listitem>

    <listitem>
     <para>
      Allow the planner to assume that empty parent tables really are empty
      (Tom Lane)
     </para>

     <para>
      Normally an empty table is assumed to have a certain minimum size for
      planning purposes; but this heuristic seems to do more harm than good
      for the parent table of an inheritance hierarchy, which often is
      permanently empty.
     </para>
    </listitem>

    <listitem>
     <para>
      Allow nested <literal>EXISTS</> queries to be optimized properly (Tom
      Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix array- and path-creating functions to ensure padding bytes are
      zeroes (Tom Lane)
     </para>

     <para>
      This avoids some situations where the planner will think that
      semantically-equal constants are not equal, resulting in poor
      optimization.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <command>EXPLAIN</> to handle gating Result nodes within
      inner-indexscan subplans (Tom Lane)
     </para>

     <para>
      The usual symptom of this oversight was <quote>bogus varno</> errors.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix btree preprocessing of <replaceable>indexedcol</> <literal>IS
      NULL</> conditions (Dean Rasheed)
     </para>

     <para>
      Such a condition is unsatisfiable if combined with any other type of
      btree-indexable condition on the same index column.  The case was
      handled incorrectly in 9.0.0 and later, leading to query output where
      there should be none.
     </para>
    </listitem>

    <listitem>
     <para>
      Work around gcc 4.6.0 bug that breaks WAL replay (Tom Lane)
     </para>

     <para>
      This could lead to loss of committed transactions after a server crash.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix dump bug for <literal>VALUES</> in a view (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Disallow <literal>SELECT FOR UPDATE/SHARE</> on sequences (Tom Lane)
     </para>

     <para>
      This operation doesn't work as expected and can lead to failures.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <command>VACUUM</> so that it always updates
      <literal>pg_class</>.<literal>reltuples</>/<literal>relpages</> (Tom
      Lane)
     </para>

     <para>
      This fixes some scenarios where autovacuum could make increasingly poor
      decisions about when to vacuum tables.
     </para>
    </listitem>

    <listitem>
     <para>
      Defend against integer overflow when computing size of a hash table (Tom
      Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix cases where <command>CLUSTER</> might attempt to access
      already-removed TOAST data (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix premature timeout failures during initial authentication transaction
      (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix portability bugs in use of credentials control messages for
      <quote>peer</> authentication (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix SSPI login when multiple roundtrips are required (Ahmed Shinwari,
      Magnus Hagander)
     </para>

     <para>
      The typical symptom of this problem was <quote>The function requested is
      not supported</> errors during SSPI login.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix failure when adding a new variable of a custom variable class to
      <filename>postgresql.conf</> (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Throw an error if <filename>pg_hba.conf</> contains <literal>hostssl</>
      but SSL is disabled (Tom Lane)
     </para>

     <para>
      This was concluded to be more user-friendly than the previous behavior
      of silently ignoring such lines.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix failure when <command>DROP OWNED BY</> attempts to remove default
      privileges on sequences (Shigeru Hanada)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix typo in <function>pg_srand48</> seed initialization (Andres Freund)
     </para>

     <para>
      This led to failure to use all bits of the provided seed.  This function
      is not used on most platforms (only those without <function>srandom</>),
      and the potential security exposure from a less-random-than-expected
      seed seems minimal in any case.
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid integer overflow when the sum of <literal>LIMIT</> and
      <literal>OFFSET</> values exceeds 2^63 (Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      Add overflow checks to <type>int4</> and <type>int8</> versions of
      <function>generate_series()</> (Robert Haas)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix trailing-zero removal in <function>to_char()</> (Marti Raudsepp)
     </para>

     <para>
      In a format with <literal>FM</> and no digit positions
      after the decimal point, zeroes to the left of the decimal point could
      be removed incorrectly.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <function>pg_size_pretty()</> to avoid overflow for inputs close to
      2^63 (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Weaken plpgsql's check for typmod matching in record values (Tom Lane)
     </para>

     <para>
      An overly enthusiastic check could lead to discarding length modifiers
      that should have been kept.
     </para>
    </listitem>

    <listitem>
     <para>
      Correctly handle quotes in locale names during <application>initdb</>
      (Heikki Linnakangas)
     </para>

     <para>
      The case can arise with some Windows locales, such as <quote>People's
      Republic of China</>.
     </para>
    </listitem>

    <listitem>
     <para>
      In <application>pg_upgrade</>, avoid dumping orphaned temporary tables
      (Bruce Momjian)
     </para>

     <para>
      This prevents situations wherein table OID assignments could get out of
      sync between old and new installations.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>pg_upgrade</> to preserve toast tables' relfrozenxids
      during an upgrade from 8.3 (Bruce Momjian)
     </para>

     <para>
      Failure to do this could lead to <filename>pg_clog</> files being
      removed too soon after the upgrade.
     </para>
    </listitem>

    <listitem>
     <para>
      In <application>pg_upgrade</>, fix the <literal>-l</> (log) option to
      work on Windows (Bruce Momjian)
     </para>
    </listitem>

    <listitem>
     <para>
      In <application>pg_ctl</>, support silent mode for service registrations
      on Windows (MauMau)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>psql</>'s counting of script file line numbers during
      <literal>COPY</> from a different file (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>pg_restore</>'s direct-to-database mode for
      <varname>standard_conforming_strings</> (Tom Lane)
     </para>

     <para>
      <application>pg_restore</> could emit incorrect commands when restoring
      directly to a database server from an archive file that had been made
      with <varname>standard_conforming_strings</> set to <literal>on</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Be more user-friendly about unsupported cases for parallel
      <application>pg_restore</> (Tom Lane)
     </para>

     <para>
      This change ensures that such cases are detected and reported before
      any restore actions have been taken.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix write-past-buffer-end and memory leak in <application>libpq</>'s
      LDAP service lookup code (Albe Laurenz)
     </para>
    </listitem>

    <listitem>
     <para>
      In <application>libpq</>, avoid failures when using nonblocking I/O
      and an SSL connection (Martin Pihlak, Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Improve libpq's handling of failures during connection startup
      (Tom Lane)
     </para>

     <para>
      In particular, the response to a server report of <function>fork()</>
      failure during SSL connection startup is now saner.
     </para>
    </listitem>

    <listitem>
     <para>
      Improve <application>libpq</>'s error reporting for SSL failures (Tom
      Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <function>PQsetvalue()</> to avoid possible crash when adding a new
      tuple to a <structname>PGresult</> originally obtained from a server
      query (Andrew Chernow)
     </para>
    </listitem>

    <listitem>
     <para>
      Make <application>ecpglib</> write <type>double</> values with 15 digits
      precision (Akira Kurosawa)
     </para>
    </listitem>

    <listitem>
     <para>
      In <application>ecpglib</>, be sure <literal>LC_NUMERIC</> setting is
      restored after an error (Michael Meskes)
     </para>
    </listitem>

    <listitem>
     <para>
      Apply upstream fix for blowfish signed-character bug (CVE-2011-2483)
      (Tom Lane)
     </para>

     <para>
      <filename>contrib/pg_crypto</>'s blowfish encryption code could give
      wrong results on platforms where char is signed (which is most),
      leading to encrypted passwords being weaker than they should be.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix memory leak in <filename>contrib/seg</> (Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <function>pgstatindex()</> to give consistent results for empty
      indexes (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Allow building with perl 5.14 (Alex Hunsaker)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix assorted issues with build and install file paths containing spaces
      (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Update time zone data files to <application>tzdata</> release 2011i
      for DST law changes in Canada, Egypt, Russia, Samoa, and South Sudan.
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-9-0-4">
  <title>Release 9.0.4</title>

  <note>
  <title>Release Date</title>
  <simpara>2011-04-18</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 9.0.3.
   For information about new features in the 9.0 major release, see
   <xref linkend="release-9-0">.
  </para>

  <sect2>
   <title>Migration to Version 9.0.4</title>

   <para>
    A dump/restore is not required for those running 9.0.X.
   </para>

   <para>
    However, if your installation was upgraded from a previous major
    release by running <application>pg_upgrade</>, you should take
    action to prevent possible data loss due to a now-fixed bug in
    <application>pg_upgrade</>.  The recommended solution is to run
    <command>VACUUM FREEZE</> on all TOAST tables.
    More information is available at <ulink
    url="http://wiki.postgresql.org/wiki/20110408pg_upgrade_fix">
    http://wiki.postgresql.org/wiki/20110408pg_upgrade_fix</ulink>.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Fix <application>pg_upgrade</>'s handling of TOAST tables
      (Bruce Momjian)
     </para>

     <para>
      The <structname>pg_class</>.<structfield>relfrozenxid</> value for
      TOAST tables was not correctly copied into the new installation
      during <application>pg_upgrade</>.  This could later result in
      <literal>pg_clog</> files being discarded while they were still
      needed to validate tuples in the TOAST tables, leading to
      <quote>could not access status of transaction</> failures.
     </para>

     <para>
      This error poses a significant risk of data loss for installations
      that have been upgraded with <application>pg_upgrade</>.  This patch
      corrects the problem for future uses of <application>pg_upgrade</>,
      but does not in itself cure the issue in installations that have been
      processed with a buggy version of <application>pg_upgrade</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Suppress incorrect <quote>PD_ALL_VISIBLE flag was incorrectly set</>
      warning (Heikki Linnakangas)
     </para>

     <para>
      <command>VACUUM</> would sometimes issue this warning in cases that
      are actually valid.
     </para>
    </listitem>

    <listitem>
     <para>
      Use better SQLSTATE error codes for hot standby conflict cases
      (Tatsuo Ishii and Simon Riggs)
     </para>

     <para>
      All retryable conflict errors now have an error code that indicates
      that a retry is possible.  Also, session closure due to the database
      being dropped on the master is now reported as
      <literal>ERRCODE_DATABASE_DROPPED</>, rather than
      <literal>ERRCODE_ADMIN_SHUTDOWN</>, so that connection poolers can
      handle the situation correctly.
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent intermittent hang in interactions of startup process with
      bgwriter process (Simon Riggs)
     </para>

     <para>
      This affected recovery in non-hot-standby cases.
     </para>
    </listitem>

    <listitem>
     <para>
      Disallow including a composite type in itself (Tom Lane)
     </para>

     <para>
      This prevents scenarios wherein the server could recurse infinitely
      while processing the composite type.  While there are some possible
      uses for such a structure, they don't seem compelling enough to
      justify the effort required to make sure it always works safely.
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid potential deadlock during catalog cache initialization
      (Nikhil Sontakke)
     </para>

     <para>
      In some cases the cache loading code would acquire share lock on a
      system index before locking the index's catalog.  This could deadlock
      against processes trying to acquire exclusive locks in the other,
      more standard order.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix dangling-pointer problem in <literal>BEFORE ROW UPDATE</> trigger
      handling when there was a concurrent update to the target tuple
      (Tom Lane)
     </para>

     <para>
      This bug has been observed to result in intermittent <quote>cannot
      extract system attribute from virtual tuple</> failures while trying to
      do <literal>UPDATE RETURNING ctid</>.  There is a very small probability
      of more serious errors, such as generating incorrect index entries for
      the updated tuple.
     </para>
    </listitem>

    <listitem>
     <para>
      Disallow <command>DROP TABLE</> when there are pending deferred trigger
      events for the table (Tom Lane)
     </para>

     <para>
      Formerly the <command>DROP</> would go through, leading to
      <quote>could not open relation with OID nnn</> errors when the
      triggers were eventually fired.
     </para>
    </listitem>

    <listitem>
     <para>
      Allow <quote>replication</> as a user name in
      <filename>pg_hba.conf</> (Andrew Dunstan)
     </para>

     <para>
      <quote>replication</> is special in the database name column, but it
      was mistakenly also treated as special in the user name column.
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent crash triggered by constant-false WHERE conditions during
      GEQO optimization (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Improve planner's handling of semi-join and anti-join cases
      (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix handling of <literal>SELECT FOR UPDATE</> in a sub-SELECT
      (Tom Lane)
     </para>

     <para>
      This bug typically led to <quote>cannot extract system attribute from
      virtual tuple</> errors.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix selectivity estimation for text search to account for NULLs
      (Jesper Krogh)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix get_actual_variable_range() to support hypothetical indexes
      injected by an index adviser plugin (Gurjeet Singh)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix PL/Python memory leak involving array slices (Daniel Popowich)
     </para>
    </listitem>

    <listitem>
     <para>
      Allow <application>libpq</>'s SSL initialization to succeed when
      user's home directory is unavailable (Tom Lane)
     </para>

     <para>
      If the SSL mode is such that a root certificate file is not required,
      there is no need to fail.  This change restores the behavior to what
      it was in pre-9.0 releases.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>libpq</> to return a useful error message for errors
      detected in <function>conninfo_array_parse</> (Joseph Adams)
     </para>

     <para>
      A typo caused the library to return NULL, rather than the
      <structname>PGconn</> structure containing the error message, to the
      application.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>ecpg</> preprocessor's handling of float constants
      (Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix parallel <application>pg_restore</> to handle comments on
      POST_DATA items correctly (Arnd Hannemann)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>pg_restore</> to cope with long lines (over 1KB) in
      TOC files (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Put in more safeguards against crashing due to division-by-zero
      with overly enthusiastic compiler optimization (Aurelien Jarno)
     </para>
    </listitem>

    <listitem>
     <para>
      Support use of dlopen() in FreeBSD and OpenBSD on MIPS (Tom Lane)
     </para>

     <para>
      There was a hard-wired assumption that this system function was not
      available on MIPS hardware on these systems.  Use a compile-time test
      instead, since more recent versions have it.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix compilation failures on HP-UX (Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid crash when trying to write to the Windows console very early
      in process startup (Rushabh Lathia)
     </para>
    </listitem>

    <listitem>
     <para>
      Support building with MinGW 64 bit compiler for Windows
      (Andrew Dunstan)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix version-incompatibility problem with <application>libintl</> on
      Windows (Hiroshi Inoue)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix usage of <application>xcopy</> in Windows build scripts to
      work correctly under Windows 7 (Andrew Dunstan)
     </para>

     <para>
      This affects the build scripts only, not installation or usage.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix path separator used by <application>pg_regress</> on Cygwin
      (Andrew Dunstan)
     </para>
    </listitem>

    <listitem>
     <para>
      Update time zone data files to <application>tzdata</> release 2011f
      for DST law changes in Chile, Cuba, Falkland Islands, Morocco, Samoa,
      and Turkey; also historical corrections for South Australia, Alaska,
      and Hawaii.
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-9-0-3">
  <title>Release 9.0.3</title>

  <note>
  <title>Release Date</title>
  <simpara>2011-01-31</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 9.0.2.
   For information about new features in the 9.0 major release, see
   <xref linkend="release-9-0">.
  </para>

  <sect2>
   <title>Migration to Version 9.0.3</title>

   <para>
    A dump/restore is not required for those running 9.0.X.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Before exiting <application>walreceiver</>, ensure all the received WAL
      is fsync'd to disk (Heikki Linnakangas)
     </para>

     <para>
      Otherwise the standby server could replay some un-synced WAL, conceivably
      leading to data corruption if the system crashes just at that point.
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid excess fsync activity in <application>walreceiver</>
      (Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      Make <command>ALTER TABLE</> revalidate uniqueness and exclusion
      constraints when needed (Noah Misch)
     </para>

     <para>
      This was broken in 9.0 by a change that was intended to suppress
      revalidation during <command>VACUUM FULL</> and <command>CLUSTER</>,
      but unintentionally affected <command>ALTER TABLE</> as well.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix EvalPlanQual for <command>UPDATE</> of an inheritance tree in which
      the tables are not all alike (Tom Lane)
     </para>

     <para>
      Any variation in the table row types (including dropped columns present
      in only some child tables) would confuse the EvalPlanQual code, leading
      to misbehavior or even crashes.  Since EvalPlanQual is only executed
      during concurrent updates to the same row, the problem was only seen
      intermittently.
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid failures when <command>EXPLAIN</> tries to display a simple-form
      <literal>CASE</> expression (Tom Lane)
     </para>

     <para>
      If the <literal>CASE</>'s test expression was a constant, the planner
      could simplify the <literal>CASE</> into a form that confused the
      expression-display code, resulting in <quote>unexpected CASE WHEN
      clause</> errors.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix assignment to an array slice that is before the existing range
      of subscripts (Tom Lane)
     </para>

     <para>
      If there was a gap between the newly added subscripts and the first
      pre-existing subscript, the code miscalculated how many entries needed
      to be copied from the old array's null bitmap, potentially leading to
      data corruption or crash.
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid unexpected conversion overflow in planner for very distant date
      values (Tom Lane)
     </para>

     <para>
      The <type>date</> type supports a wider range of dates than can be
      represented by the <type>timestamp</> types, but the planner assumed it
      could always convert a date to timestamp with impunity.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix PL/Python crash when an array contains null entries (Alex Hunsaker)
     </para>
    </listitem>

    <listitem>
     <para>
      Remove <application>ecpg</>'s fixed length limit for constants defining
      an array dimension (Michael Meskes)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix erroneous parsing of <type>tsquery</> values containing
      <literal>... &amp; !(subexpression) | ...</literal> (Tom Lane)
     </para>

     <para>
      Queries containing this combination of operators were not executed
      correctly.  The same error existed in <filename>contrib/intarray</>'s
      <type>query_int</> type and <filename>contrib/ltree</>'s
      <type>ltxtquery</> type.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix buffer overrun in <filename>contrib/intarray</>'s input function
      for the <type>query_int</> type (Apple)
     </para>

     <para>
      This bug is a security risk since the function's return address could
      be overwritten.  Thanks to Apple Inc's security team for reporting this
      issue and supplying the fix.  (CVE-2010-4015)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix bug in <filename>contrib/seg</>'s GiST picksplit algorithm
      (Alexander Korotkov)
     </para>

     <para>
      This could result in considerable inefficiency, though not actually
      incorrect answers, in a GiST index on a <type>seg</> column.
      If you have such an index, consider <command>REINDEX</>ing it after
      installing this update.  (This is identical to the bug that was fixed in
      <filename>contrib/cube</> in the previous update.)
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-9-0-2">
  <title>Release 9.0.2</title>

  <note>
  <title>Release Date</title>
  <simpara>2010-12-16</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 9.0.1.
   For information about new features in the 9.0 major release, see
   <xref linkend="release-9-0">.
  </para>

  <sect2>
   <title>Migration to Version 9.0.2</title>

   <para>
    A dump/restore is not required for those running 9.0.X.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Force the default
      <link linkend="guc-wal-sync-method"><varname>wal_sync_method</></link>
      to be <literal>fdatasync</> on Linux (Tom Lane, Marti Raudsepp)
     </para>

     <para>
      The default on Linux has actually been <literal>fdatasync</> for many
      years, but recent kernel changes caused <productname>PostgreSQL</> to
      choose <literal>open_datasync</> instead.  This choice did not result
      in any performance improvement, and caused outright failures on
      certain filesystems, notably <literal>ext4</> with the
      <literal>data=journal</> mount option.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <quote>too many KnownAssignedXids</> error during Hot Standby
      replay (Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix race condition in lock acquisition during Hot Standby (Simon Riggs)
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid unnecessary conflicts during Hot Standby (Simon Riggs)
     </para>

     <para>
      This fixes some cases where replay was considered to conflict with
      standby queries (causing delay of replay or possibly cancellation of
      the queries), but there was no real conflict.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix assorted bugs in WAL replay logic for GIN indexes (Tom Lane)
     </para>

     <para>
      This could result in <quote>bad buffer id: 0</> failures or
      corruption of index contents during replication.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix recovery from base backup when the starting checkpoint WAL record
      is not in the same WAL segment as its redo point (Jeff Davis)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix corner-case bug when streaming replication is enabled immediately
      after creating the master database cluster (Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix persistent slowdown of autovacuum workers when multiple workers
      remain active for a long time (Tom Lane)
     </para>

     <para>
      The effective <varname>vacuum_cost_limit</> for an autovacuum worker
      could drop to nearly zero if it processed enough tables, causing it
      to run extremely slowly.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix long-term memory leak in autovacuum launcher (Alvaro Herrera)
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid failure when trying to report an impending transaction
      wraparound condition from outside a transaction (Tom Lane)
     </para>

     <para>
      This oversight prevented recovery after transaction wraparound got
      too close, because database startup processing would fail.
     </para>
    </listitem>

    <listitem>
     <para>
      Add support for detecting register-stack overrun on <literal>IA64</>
      (Tom Lane)
     </para>

     <para>
      The <literal>IA64</> architecture has two hardware stacks.  Full
      prevention of stack-overrun failures requires checking both.
     </para>
    </listitem>

    <listitem>
     <para>
      Add a check for stack overflow in <function>copyObject()</> (Tom Lane)
     </para>

     <para>
      Certain code paths could crash due to stack overflow given a
      sufficiently complex query.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix detection of page splits in temporary GiST indexes (Heikki
      Linnakangas)
     </para>

     <para>
      It is possible to have a <quote>concurrent</> page split in a
      temporary index, if for example there is an open cursor scanning the
      index when an insertion is done.  GiST failed to detect this case and
      hence could deliver wrong results when execution of the cursor
      continued.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix error checking during early connection processing (Tom Lane)
     </para>

     <para>
      The check for too many child processes was skipped in some cases,
      possibly leading to postmaster crash when attempting to add the new
      child process to fixed-size arrays.
     </para>
    </listitem>

    <listitem>
     <para>
      Improve efficiency of window functions (Tom Lane)
     </para>

     <para>
      Certain cases where a large number of tuples needed to be read in
      advance, but <varname>work_mem</> was large enough to allow them all
      to be held in memory, were unexpectedly slow.
      <function>percent_rank()</>, <function>cume_dist()</> and
      <function>ntile()</> in particular were subject to this problem.
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid memory leakage while <command>ANALYZE</>'ing complex index
      expressions (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Ensure an index that uses a whole-row Var still depends on its table
      (Tom Lane)
     </para>

     <para>
      An index declared like <literal>create index i on t (foo(t.*))</>
      would not automatically get dropped when its table was dropped.
     </para>
    </listitem>

    <listitem>
     <para>
      Add missing support in <command>DROP OWNED BY</> for removing foreign
      data wrapper/server privileges belonging to a user (Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      Do not <quote>inline</> a SQL function with multiple <literal>OUT</>
      parameters (Tom Lane)
     </para>

     <para>
      This avoids a possible crash due to loss of information about the
      expected result rowtype.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix crash when inline-ing a set-returning function whose argument list
      contains a reference to an inline-able user function (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Behave correctly if <literal>ORDER BY</>, <literal>LIMIT</>,
      <literal>FOR UPDATE</>, or <literal>WITH</> is attached to the
      <literal>VALUES</> part of <literal>INSERT ... VALUES</> (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Make the <literal>OFF</> keyword unreserved (Heikki Linnakangas)
     </para>

     <para>
      This prevents problems with using <literal>off</> as a variable name in
      <application>PL/pgSQL</>.  That worked before 9.0, but was now broken
      because <application>PL/pgSQL</> now treats all core reserved words
      as reserved.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix constant-folding of <literal>COALESCE()</> expressions (Tom Lane)
     </para>

     <para>
      The planner would sometimes attempt to evaluate sub-expressions that
      in fact could never be reached, possibly leading to unexpected errors.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <quote>could not find pathkey item to sort</> planner failure
      with comparison of whole-row Vars (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix postmaster crash when connection acceptance
      (<function>accept()</> or one of the calls made immediately after it)
      fails, and the postmaster was compiled with GSSAPI support (Alexander
      Chernikov)
     </para>
    </listitem>

    <listitem>
     <para>
      Retry after receiving an invalid response packet from a RADIUS
      authentication server (Magnus Hagander)
     </para>

     <para>
      This fixes a low-risk potential denial of service condition.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix missed unlink of temporary files when <varname>log_temp_files</>
      is active (Tom Lane)
     </para>

     <para>
      If an error occurred while attempting to emit the log message, the
      unlink was not done, resulting in accumulation of temp files.
     </para>
    </listitem>

    <listitem>
     <para>
      Add print functionality for <structname>InhRelation</> nodes (Tom Lane)
     </para>

     <para>
      This avoids a failure when <varname>debug_print_parse</> is enabled
      and certain types of query are executed.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix incorrect calculation of distance from a point to a horizontal
      line segment (Tom Lane)
     </para>

     <para>
      This bug affected several different geometric distance-measurement
      operators.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix incorrect calculation of transaction status in
      <application>ecpg</> (Itagaki Takahiro)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix errors in <application>psql</>'s Unicode-escape support (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Speed up parallel <application>pg_restore</> when the archive
      contains many large objects (blobs) (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>PL/pgSQL</>'s handling of <quote>simple</>
      expressions to not fail in recursion or error-recovery cases (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>PL/pgSQL</>'s error reporting for no-such-column
      cases (Tom Lane)
     </para>

     <para>
      As of 9.0, it would sometimes report <quote>missing FROM-clause entry
      for table foo</> when <quote>record foo has no field bar</> would be
      more appropriate.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>PL/Python</> to honor typmod (i.e., length or
      precision restrictions) when assigning to tuple fields (Tom Lane)
     </para>

     <para>
      This fixes a regression from 8.4.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>PL/Python</>'s handling of set-returning functions
      (Jan Urbanski)
     </para>

     <para>
      Attempts to call SPI functions within the iterator generating a set
      result would fail.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix bug in <filename>contrib/cube</>'s GiST picksplit algorithm
      (Alexander Korotkov)
     </para>

     <para>
      This could result in considerable inefficiency, though not actually
      incorrect answers, in a GiST index on a <type>cube</> column.
      If you have such an index, consider <command>REINDEX</>ing it after
      installing this update.
     </para>
    </listitem>

    <listitem>
     <para>
      Don't emit <quote>identifier will be truncated</> notices in
      <filename>contrib/dblink</> except when creating new connections
      (Itagaki Takahiro)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix potential coredump on missing public key in
      <filename>contrib/pgcrypto</> (Marti Raudsepp)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix buffer overrun in <filename>contrib/pg_upgrade</> (Hernan Gonzalez)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix memory leak in <filename>contrib/xml2</>'s XPath query functions
      (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Update time zone data files to <application>tzdata</> release 2010o
      for DST law changes in Fiji and Samoa;
      also historical corrections for Hong Kong.
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-9-0-1">
  <title>Release 9.0.1</title>

  <note>
  <title>Release Date</title>
  <simpara>2010-10-04</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 9.0.0.
   For information about new features in the 9.0 major release, see
   <xref linkend="release-9-0">.
  </para>

  <sect2>
   <title>Migration to Version 9.0.1</title>

   <para>
    A dump/restore is not required for those running 9.0.X.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Use a separate interpreter for each calling SQL userid in PL/Perl and
      PL/Tcl (Tom Lane)
     </para>

     <para>
      This change prevents security problems that can be caused by subverting
      Perl or Tcl code that will be executed later in the same session under
      another SQL user identity (for example, within a <literal>SECURITY
      DEFINER</> function).  Most scripting languages offer numerous ways that
      that might be done, such as redefining standard functions or operators
      called by the target function.  Without this change, any SQL user with
      Perl or Tcl language usage rights can do essentially anything with the
      SQL privileges of the target function's owner.
     </para>

     <para>
      The cost of this change is that intentional communication among Perl
      and Tcl functions becomes more difficult.  To provide an escape hatch,
      PL/PerlU and PL/TclU functions continue to use only one interpreter
      per session.  This is not considered a security issue since all such
      functions execute at the trust level of a database superuser already.
     </para>

     <para>
      It is likely that third-party procedural languages that claim to offer
      trusted execution have similar security issues.  We advise contacting
      the authors of any PL you are depending on for security-critical
      purposes.
     </para>

     <para>
      Our thanks to Tim Bunce for pointing out this issue (CVE-2010-3433).
     </para>
    </listitem>

    <listitem>
     <para>
      Improve <function>pg_get_expr()</> security fix so that the function
      can still be used on the output of a sub-select (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix incorrect placement of placeholder evaluation (Tom Lane)
     </para>

     <para>
      This bug could result in query outputs being non-null when they
      should be null, in cases where the inner side of an outer join
      is a sub-select with non-strict expressions in its output list.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix join removal's handling of placeholder expressions (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possible duplicate scans of <literal>UNION ALL</> member relations
      (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent infinite loop in ProcessIncomingNotify() after unlistening
      (Jeff Davis)
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent show_session_authorization() from crashing within autovacuum
      processes (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Re-allow input of Julian dates prior to 0001-01-01 AD (Tom Lane)
     </para>

     <para>
      Input such as <literal>'J100000'::date</> worked before 8.4,
      but was unintentionally broken by added error-checking.
     </para>
    </listitem>

    <listitem>
     <para>
      Make psql recognize <command>DISCARD ALL</> as a command that should
      not be encased in a transaction block in autocommit-off mode
      (Itagaki Takahiro)
     </para>
    </listitem>

    <listitem>
     <para>
      Update build infrastructure and documentation to reflect the source code
      repository's move from CVS to Git (Magnus Hagander and others)
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-9-0">
  <title>Release 9.0</title>

  <note>
   <title>Release Date</title>
   <simpara>2010-09-20</simpara>
  </note>

  <sect2>
   <title>Overview</title>

   <para>
    This release of
    <productname>PostgreSQL</> adds features that have been requested
    for years, such as easy-to-use replication, a mass permission-changing
    facility, and anonymous code blocks. While past major releases have
    been conservative in their scope, this release shows a
    bold new desire to provide facilities that new and existing
    users of <productname>PostgreSQL</> will embrace. This has all
    been done with few incompatibilities. Major enhancements include:
   </para>

   <itemizedlist>

    <!-- This list duplicates items below, but without authors or details-->

    <listitem>

     <para>
      Built-in replication based on log shipping.  This advance consists of
      two features: Streaming Replication, allowing continuous archive
      (<acronym>WAL</>) files to be streamed over a network connection to a
      standby server, and Hot Standby, allowing continuous archive standby
      servers to execute read-only queries.  The net effect is to support a
      single master with multiple read-only slave servers.
     </para>
    </listitem>

    <listitem>
     <para>
      Easier database object permissions management. <link
      linkend="SQL-GRANT"><command>GRANT</>/<command>REVOKE IN
      SCHEMA</></link> supports mass permissions changes on existing objects,
      while <link linkend="SQL-ALTERDEFAULTPRIVILEGES"><command>ALTER DEFAULT
      PRIVILEGES</></link> allows control of privileges for objects created in
      the future.  Large objects (BLOBs) now support permissions management as
      well.
     </para>
    </listitem>

    <listitem>
     <para>
      Broadly enhanced stored procedure support.
      The <link linkend="SQL-DO"><command>DO</></link> statement supports
      ad-hoc or <quote>anonymous</> code blocks.
      Functions can now be called using named parameters.
      <link linkend="plpgsql">PL/pgSQL</link> is now installed by default, and
      <link linkend="plperl">PL/Perl</link> and <link
      linkend="plpython">PL/Python</link> have been enhanced in several ways,
      including support for Python3.
     </para>
    </listitem>

    <listitem>
     <para>
      Full support for <link linkend="install-windows">64-bit
      <productname>Windows</></link>.
     </para>
    </listitem>

    <listitem>
     <para>
      More advanced reporting queries, including additional windowing options
      (<literal>PRECEDING</> and <literal>FOLLOWING</>) and the ability to
      control the order in which values are fed to aggregate functions.
     </para>
    </listitem>

    <listitem>
     <para>
      New trigger features, including
      SQL-standard-compliant <link
      linkend="SQL-CREATETRIGGER">per-column triggers</link> and
      conditional trigger execution.
     </para>
    </listitem>

    <listitem>
     <para>
      <link linkend="SQL-CREATETABLE-compatibility">Deferrable
      unique constraints</link>. Mass updates to unique keys are now possible
      without trickery.
     </para>
    </listitem>

    <listitem>
     <para>
      <link linkend="ddl-constraints-exclusion">Exclusion constraints</link>.
      These provide a generalized version of unique constraints, allowing
      enforcement of complex conditions.
     </para>
    </listitem>

    <listitem>
     <para>
      New and enhanced security features, including RADIUS authentication,
      LDAP authentication improvements, and a new contrib module
      <link linkend="passwordcheck"><filename>passwordcheck</></link>
      for testing password strength.
     </para>
    </listitem>

    <listitem>
     <para>
      New high-performance implementation of the
      <link linkend="SQL-LISTEN"><command>LISTEN</></link>/<link
      linkend="SQL-NOTIFY"><command>NOTIFY</></link> feature.
      Pending events are now stored in a memory-based queue rather than
      a table.  Also, a <quote>payload</> string can be sent with each
      event, rather than transmitting just an event name as before.
     </para>
    </listitem>

    <listitem>
     <para>
      New implementation of
      <link linkend="SQL-VACUUM"><command>VACUUM FULL</></link>.
      This command now rewrites the entire table and indexes, rather than
      moving individual rows to compact space.  It is substantially faster
      in most cases, and no longer results in index bloat.
     </para>
    </listitem>

    <listitem>
     <para>
      New contrib module
      <link linkend="pgupgrade"><filename>pg_upgrade</></link>
      to support in-place upgrades from 8.3 or 8.4 to 9.0.
     </para>
    </listitem>

    <listitem>
     <para>
      Multiple performance enhancements for specific types of queries,
      including elimination of unnecessary joins.  This helps optimize some
      automatically-generated queries, such as those produced by
      object-relational mappers (ORMs).
     </para>
    </listitem>

    <listitem>
     <para>
      <link linkend="SQL-EXPLAIN "><command>EXPLAIN</></link> enhancements.
      The output is now available in JSON, XML, or YAML format, and includes
      buffer utilization and other data not previously available.
     </para>
    </listitem>

    <listitem>
     <para>
      <link linkend="hstore"><filename>hstore</></link> improvements,
      including new functions and greater data capacity.
     </para>
    </listitem>

   </itemizedlist>

   <para>
    The above items are explained in more detail in the sections below.
   </para>

  </sect2>

  <sect2>

  <title>Migration to Version 9.0</title>

  <para>
   A dump/restore using <application>pg_dump</application>,
   or use of <application>pg_upgrade</application>, is required
   for those wishing to migrate data from any previous
   release.
  </para>

  <para>
   Version 9.0 contains a number of changes that selectively break backwards
   compatibility in order to support new features and code quality
   improvements.  In particular, users who make extensive use of PL/pgSQL,
   Point-In-Time Recovery (PITR), or Warm Standby should test their
   applications because of slight user-visible changes in those areas.
   Observe the following incompatibilities:
  </para>

  <sect3>
   <title>Server Settings</title>

   <itemizedlist>

    <listitem>
     <para>
      Remove server parameter <varname>add_missing_from</>, which was
      defaulted to off for many years (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Remove server parameter <varname>regex_flavor</>, which
      was defaulted to <link
      linkend="posix-syntax-details"><literal>advanced</></link>
      for many years (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      <link linkend="guc-archive-mode"><varname>archive_mode</></link>
      now only affects <link
      linkend="guc-archive-command"><varname>archive_command</></link>;
      a new setting, <link
      linkend="guc-wal-level"><varname>wal_level</></link>, affects
      the contents of the write-ahead log (Heikki Linnakangas)
     </para>
    </listitem>

    <listitem>
     <para>
      <link linkend="guc-log-temp-files"><varname>log_temp_files</></link>
      now uses default file size units of kilobytes (Robert Haas)
     </para>
    </listitem>

   </itemizedlist>

  </sect3>

  <sect3>
   <title>Queries</title>

   <itemizedlist>

   <listitem>
    <para>
     When querying a <link linkend="ddl-inherit">parent table</link>,
     do not do any separate permission checks on child tables
     scanned as part of the query (Peter Eisentraut)
    </para>

    <para>
     The SQL standard specifies this behavior, and it is also much more
     convenient in practice than the former behavior of checking permissions
     on each child as well as the parent.
    </para>
   </listitem>

   </itemizedlist>

  </sect3>

  <sect3>
   <title>Data Types</title>

   <itemizedlist>

    <listitem>
     <para>
      <link linkend="datatype-binary"><type>bytea</></link> output now
      appears in hex format by default (Peter Eisentraut)
     </para>

     <para>
      The server parameter <link
      linkend="guc-bytea-output"><varname>bytea_output</></link> can be
      used to select the traditional output format if needed for
      compatibility.
     </para>
    </listitem>

    <listitem>
     <para>
      Array input now considers only plain ASCII whitespace characters
      to be potentially ignorable; it will never ignore non-ASCII characters,
      even if they are whitespace according to some locales (Tom Lane)
     </para>

     <para>
      This avoids some corner cases where array values could be interpreted
      differently depending on the server's locale settings.
     </para>
    </listitem>

   <listitem>
    <para>
     Improve standards compliance of <link
     linkend="functions-similarto-regexp"><literal>SIMILAR TO</></link>
     patterns and SQL-style <function>substring()</> patterns (Tom Lane)
    </para>

    <para>
     This includes treating <literal>?</> and <literal>{...}</> as
     pattern metacharacters, while they were simple literal characters
     before; that corresponds to new features added in SQL:2008.
     Also, <literal>^</> and <literal>$</> are now treated as simple
     literal characters; formerly they were treated as metacharacters,
     as if the pattern were following POSIX rather than SQL rules.
     Also, in SQL-standard <function>substring()</>, use of parentheses
     for nesting no longer interferes with capturing of a substring.
     Also, processing of bracket expressions (character classes) is
     now more standards-compliant.
    </para>
   </listitem>

   <listitem>
    <para>
     Reject negative length values in 3-parameter <link
     linkend="functions-string-sql"><function>substring()</></link>
     for bit strings, per the SQL standard (Tom Lane)
    </para>
   </listitem>

   <listitem>
    <para>
     Make <function>date_trunc</> truncate rather than round when reducing
     precision of fractional seconds (Tom Lane)
    </para>

    <para>
     The code always acted this way for integer-based dates/times.
     Now float-based dates/times behave similarly.
    </para>
   </listitem>

  </itemizedlist>

  </sect3>

  <sect3>
   <title>Object Renaming</title>

   <itemizedlist>

    <listitem>
     <para>
      Tighten enforcement of column name consistency during <command>RENAME</>
      when a child table inherits the same column from multiple unrelated
      parents (KaiGai Kohei)
     </para>
    </listitem>

    <listitem>
     <para>
      No longer automatically rename indexes and index columns when the
      underlying table columns are renamed (Tom Lane)
     </para>

     <para>
      Administrators can still rename such indexes and columns manually.
      This change will require an update of the JDBC driver, and possibly other
      drivers, so that unique indexes are correctly recognized after a rename.
     </para>
    </listitem>

    <listitem>
     <para>
      <command>CREATE OR REPLACE FUNCTION</command> can no longer change
      the declared names of function parameters (Pavel Stehule)
     </para>

     <para>
      In order to avoid creating ambiguity in named-parameter calls, it is
      no longer allowed to change the aliases for input parameters
      in the declaration of an existing function (although names can still
      be assigned to previously unnamed parameters).  You now have to
      <command>DROP</command> and recreate the function to do that.
     </para>
    </listitem>

   </itemizedlist>

  </sect3>

  <sect3>
   <title>PL/pgSQL</title>

   <itemizedlist>

    <listitem>
     <para>
      PL/pgSQL now throws an error if a variable name conflicts with a
      column name used in a query (Tom Lane)
     </para>

     <para>
      The former behavior was to bind ambiguous names to PL/pgSQL variables
      in preference to query columns, which often resulted in surprising
      misbehavior. Throwing an error allows easy detection of ambiguous
      situations.  Although it's recommended that functions encountering this
      type of error be modified to remove the conflict, the old behavior can
      be restored if necessary via the configuration parameter <link
      linkend="plpgsql-var-subst"><varname>plpgsql.variable_conflict</></link>,
      or via the per-function option <literal>#variable_conflict</>.
     </para>
    </listitem>

    <listitem>
     <para>
      PL/pgSQL no longer allows variable names that match certain SQL
      reserved words (Tom Lane)
     </para>

     <para>
      This is a consequence of aligning the PL/pgSQL parser to match the
      core SQL parser more closely.  If necessary,
      variable names can be double-quoted to avoid this restriction.
     </para>
    </listitem>

    <listitem>
     <para>
      PL/pgSQL now requires columns of composite results to match the
      expected type modifier as well as base type (Pavel Stehule, Tom Lane)
     </para>

     <para>
      For example, if a column of the result type is declared as
      <literal>NUMERIC(30,2)</>, it is no longer acceptable to return a
      <literal>NUMERIC</> of some other precision in that column.  Previous
      versions neglected to check the type modifier and would thus allow
      result rows that didn't actually conform to the declared restrictions.
     </para>
    </listitem>

    <listitem>
     <para>
      PL/pgSQL now treats selection into composite fields more consistently
      (Tom Lane)
     </para>

     <para>
      Formerly, a statement like
      <literal>SELECT ... INTO <replaceable>rec</>.<replaceable>fld</> FROM ...</literal>
      was treated as a scalar assignment even if the record field
      <replaceable>fld</> was of composite type.  Now it is treated as a
      record assignment, the same as when the <literal>INTO</> target is a
      regular variable of composite type.  So the values to be assigned to the
      field's subfields should be written as separate columns of the
      <command>SELECT</> list, not as a <literal>ROW(...)</> construct as in
      previous versions.
     </para>

     <para>
      If you need to do this in a way that will work in both 9.0 and previous
      releases, you can write something like
      <literal><replaceable>rec</>.<replaceable>fld</> := ROW(...) FROM ...</literal>.
     </para>
    </listitem>

    <listitem>
     <para>
      Remove PL/pgSQL's <literal>RENAME</> declaration (Tom Lane)
     </para>

     <para>
      Instead of <literal>RENAME</>, use <link
      linkend="plpgsql-declaration-alias"><literal>ALIAS</></link>,
      which can now create an alias for any variable, not only dollar sign
      parameter names (such as <literal>$1</>) as before.
     </para>
    </listitem>
   </itemizedlist>

  </sect3>

  <sect3>
   <title>Other Incompatibilities</title>

   <itemizedlist>

    <listitem>
     <para>
      Deprecate use of <literal>=&gt;</> as an operator name (Robert Haas)
     </para>

     <para>
      Future versions of <productname>PostgreSQL</> will probably reject
      this operator name entirely, in order to support the SQL-standard
      notation for named function parameters.  For the moment, it is
      still allowed, but a warning is emitted when such an operator is
      defined.
     </para>
    </listitem>

    <listitem>
     <para>
      Remove support for platforms that don't have a working 64-bit
      integer data type (Tom Lane)
     </para>

     <para>
      It is believed all still-supported platforms have working 64-bit
      integer data types.
     </para>
    </listitem>

   </itemizedlist>
  </sect3>
 </sect2>

 <sect2>
  <title>Changes</title>
   <para>
    Version 9.0 has an unprecedented number of new major features,
    and over 200 enhancements, improvements, new commands,
    new functions, and other changes.
   </para>

  <sect3>
   <title>Server</title>

   <sect4>
    <title>Continuous Archiving and Streaming Replication</title>

    <para>
     PostgreSQL's existing standby-server capability has been expanded both to
     support read-only queries on standby servers and to greatly reduce
     the lag between master and standby servers.  For many users, this
     will be a useful and low-administration form of replication, either
     for high availability or for horizontal scalability.
    </para>

    <itemizedlist>
     <listitem>
      <para>
       Allow a standby server to accept read-only queries
       (Simon Riggs, Heikki Linnakangas)
      </para>

      <para>
       This feature is called Hot Standby. There are new
       <filename>postgresql.conf</> and <filename>recovery.conf</>
       settings to control this feature, as well as extensive
       <link linkend="hot-standby">documentation</link>.
      </para>
     </listitem>

     <listitem>
      <para>
       Allow write-ahead log (<acronym>WAL</>) data to be streamed to a
       standby server (Fujii Masao, Heikki Linnakangas)
      </para>

      <para>
       This feature is called Streaming Replication.
       Previously <acronym>WAL</> data could be sent to standby servers only
       in units of entire <acronym>WAL</> files (normally 16 megabytes each).
       Streaming Replication eliminates this inefficiency and allows updates
       on the master to be propagated to standby servers with very little
       delay.  There are new <filename>postgresql.conf</> and
       <filename>recovery.conf</> settings to control this feature, as well as
       extensive <link linkend="streaming-replication">documentation</link>.
      </para>
     </listitem>

     <listitem>
      <para>
       Add <link
       linkend="functions-recovery-info-table"><function>pg_last_xlog_receive_location()</></link>
       and <function>pg_last_xlog_replay_location()</>, which
       can be used to monitor standby server <acronym>WAL</>
       activity (Simon Riggs, Fujii Masao, Heikki Linnakangas)
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

   <sect4>
    <title>Performance</title>

    <itemizedlist>

     <listitem>
      <para>
       Allow per-tablespace values to be set for sequential and random page
       cost estimates (<varname>seq_page_cost</>/<varname>random_page_cost</>)
       via <link linkend="SQL-ALTERTABLESPACE"><command>ALTER TABLESPACE
       ... SET/RESET</></link> (Robert Haas)
      </para>
     </listitem>

     <listitem>
      <para>
       Improve performance and reliability of EvalPlanQual rechecks in join
       queries (Tom Lane)
      </para>

      <para>
       <command>UPDATE</>, <command>DELETE</>, and <command>SELECT FOR
       UPDATE/SHARE</> queries that involve joins will now behave much better
       when encountering freshly-updated rows.
      </para>
     </listitem>

     <listitem>
      <para>
       Improve performance of <link
       linkend="SQL-TRUNCATE"><command>TRUNCATE</></link> when
       the table was created or truncated earlier in the same transaction
       (Tom Lane)
      </para>
     </listitem>

     <listitem>
      <para>
       Improve performance of finding inheritance child tables (Tom Lane)
      </para>
     </listitem>

     </itemizedlist>

   </sect4>

   <sect4>
    <title>Optimizer</title>

    <itemizedlist>

     <listitem>
      <para>
       Remove unnecessary <link linkend="queries-join">outer
       joins</link> (Robert Haas)
      </para>

      <para>
       Outer joins where the inner side is unique and not referenced above
       the join are unnecessary and are therefore now removed.  This will
       accelerate many automatically generated queries, such as those created
       by object-relational mappers (ORMs).
      </para>
     </listitem>

     <listitem>
      <para>
       Allow <literal>IS NOT NULL</> restrictions to use indexes (Tom Lane)
      </para>

      <para>
       This is particularly useful for finding
       <function>MAX()</>/<function>MIN()</> values in indexes that
       contain many null values.
      </para>
     </listitem>

     <listitem>
      <para>
       Improve the optimizer's choices about when to use materialize nodes,
       and when to use sorting versus hashing for <literal>DISTINCT</>
       (Tom Lane)
      </para>
     </listitem>

     <listitem>
      <para>
       Improve the optimizer's equivalence detection for expressions involving
       <type>boolean</> <literal>&lt;&gt;</> operators (Tom Lane)
      </para>
     </listitem>
    </itemizedlist>
   </sect4>

   <sect4>
    <title><link linkend="geqo">GEQO</link></title>

    <itemizedlist>

     <listitem>
      <para>
       Use the same random seed every time GEQO plans a query (Andres
       Freund)
      </para>

      <para>
       While the Genetic Query Optimizer (GEQO) still selects
       random plans, it now always selects the same random plans for identical
       queries, thus giving more consistent performance. You can modify <link
       linkend="guc-geqo-seed"><varname>geqo_seed</></link> to experiment with
       alternative plans.
      </para>
     </listitem>

     <listitem>
      <para>
       Improve GEQO plan selection (Tom Lane)
      </para>

      <para>
       This avoids the rare error <quote>failed to make a valid plan</>,
       and should also improve planning speed.
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

   <sect4>
    <title>Optimizer Statistics</title>

    <itemizedlist>

     <listitem>
      <para>
       Improve <link linkend="SQL-ANALYZE"><command>ANALYZE</></link>
       to support inheritance-tree statistics (Tom Lane)
      </para>

      <para>
       This is particularly useful for partitioned tables.  However,
       autovacuum does not yet automatically re-analyze parent tables
       when child tables change.
      </para>
     </listitem>

     <listitem>
      <para>
       Improve <link linkend="routine-vacuuming">autovacuum</link>'s
       detection of when re-analyze is necessary (Tom Lane)
      </para>
     </listitem>

     <listitem>
      <para>
       Improve optimizer's estimation for greater/less-than comparisons
       (Tom Lane)
      </para>

      <para>
       When looking up statistics for greater/less-than comparisons,
       if the comparison value is in the first or last histogram bucket,
       use an index (if available) to fetch the current actual column
       minimum or maximum.  This greatly improves the accuracy of estimates
       for comparison values near the ends of the data range, particularly
       if the range is constantly changing due to addition of new data.
      </para>
     </listitem>

     <listitem>
      <para>
       Allow setting of number-of-distinct-values statistics using <link
       linkend="SQL-ALTERTABLE"><command>ALTER TABLE</></link>
       (Robert Haas)
      </para>

      <para>
       This allows users to override the estimated number or percentage of
       distinct values for a column. This statistic is normally computed by
       <command>ANALYZE</>, but the estimate can be poor, especially on tables
       with very large numbers of rows.
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

   <sect4>
    <title>Authentication</title>

    <itemizedlist>

     <listitem>
      <para>
       Add support for <link
       linkend="auth-radius"><acronym>RADIUS</></link> (Remote
       Authentication Dial In User Service) authentication
       (Magnus Hagander)
      </para>
     </listitem>

     <listitem>
      <para>
       Allow <link linkend="auth-ldap"><acronym>LDAP</></link>
       (Lightweight Directory Access Protocol) authentication
       to operate in <quote>search/bind</> mode
       (Robert Fleming, Magnus Hagander)
      </para>

      <para>
       This allows the user to be looked up first, then the system uses
       the <acronym>DN</> (Distinguished Name) returned for that user.
      </para>
     </listitem>

     <listitem>
      <para>
       Add <link
       linkend="auth-pg-hba-conf"><literal>samehost</></link>
       and <literal>samenet</> designations to
       <filename>pg_hba.conf</> (Stef Walter)
      </para>

      <para>
       These match the server's <acronym>IP</> address and subnet address
       respectively.
      </para>
     </listitem>

     <listitem>
      <para>
       Pass trusted SSL root certificate names to the client so the client
       can return an appropriate client certificate (Craig Ringer)
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

   <sect4>
    <title>Monitoring</title>

    <itemizedlist>

     <listitem>
      <para>
       Add the ability for clients to set an <link
       linkend="libpq-connect-application-name">application
       name</link>, which is displayed in
       <structname>pg_stat_activity</> (Dave Page)
      </para>

      <para>
       This allows administrators to characterize database traffic
       and troubleshoot problems by source application.
      </para>
     </listitem>

     <listitem>
      <para>
       Add a SQLSTATE option (<literal>%e</>) to <link
       linkend="guc-log-line-prefix"><varname>log_line_prefix</></link>
       (Guillaume Smet)
      </para>

      <para>
       This allows users to compile statistics on errors and messages
       by error code number.
      </para>

     </listitem>

     <listitem>
      <para>
       Write to the Windows event log in <acronym>UTF16</> encoding
       (Itagaki Takahiro)
      </para>

      <para>
       Now there is true multilingual support for PostgreSQL log messages
       on Windows.
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

   <sect4>
    <title>Statistics Counters</title>

    <itemizedlist>

     <listitem>
      <para>
       Add <link
       linkend="monitoring-stats-funcs-table"><function>pg_stat_reset_shared('bgwriter')</></link>
       to reset the cluster-wide shared statistics for the
       background writer (Greg Smith)
      </para>
     </listitem>

     <listitem>
      <para>
       Add <link
       linkend="monitoring-stats-funcs-table"><function>pg_stat_reset_single_table_counters()</></link>
       and <function>pg_stat_reset_single_function_counters()</>
       to allow resetting the statistics counters for individual
       tables and functions (Magnus Hagander)
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

   <sect4>
    <title>Server Settings</title>

    <itemizedlist>

     <listitem>
      <para>
       Allow setting of configuration parameters based on <link
       linkend="sql-alterrole">database/role combinations</link>
       (Alvaro Herrera)
      </para>

      <para>
       Previously only per-database and per-role settings were possible,
       not combinations. All role and database settings are now stored
       in the new <structname>pg_db_role_setting</> system catalog. A new
       <application>psql</> command <literal>\drds</> shows these settings.
       The legacy system views <structname>pg_roles</>,
       <structname>pg_shadow</>, and <structname>pg_user</>
       do not show combination settings, and therefore no longer
       completely represent the configuration for a user or database.
      </para>
     </listitem>

     <listitem>
      <para>
       Add server parameter <link
       linkend="guc-bonjour"><varname>bonjour</></link>, which
       controls whether a Bonjour-enabled server advertises
       itself via <productname>Bonjour</> (Tom Lane)
      </para>

      <para>
       The default is off, meaning it does not advertise.  This allows
       packagers to distribute Bonjour-enabled builds without worrying
       that individual users might not want the feature.
      </para>
     </listitem>

     <listitem>
      <para>
       Add server parameter <link
       linkend="guc-enable-material"><varname>enable_material</></link>, which
       controls the use of materialize nodes in the optimizer
       (Robert Haas)
      </para>

      <para>
       The default is on.  When off, the optimizer will not add
       materialize nodes purely for performance reasons, though they
       will still be used when necessary for correctness.
      </para>
     </listitem>

     <listitem>
      <para>
       Change server parameter <link
       linkend="guc-log-temp-files"><varname>log_temp_files</></link> to
       use default file size units of kilobytes (Robert Haas)
      </para>

      <para>
       Previously this setting was interpreted in bytes if no units were
       specified.
      </para>
     </listitem>

     <listitem>
      <para>
       Log changes of parameter values when <filename>postgresql.conf</> is
       reloaded (Peter Eisentraut)
      </para>

      <para>
       This lets administrators and security staff audit changes of database
       settings, and is also very convenient for checking the effects of
       <filename>postgresql.conf</> edits.
      </para>
     </listitem>

     <listitem>
      <para>
       Properly enforce superuser permissions for custom server parameters
       (Tom Lane)
      </para>

      <para>
       Non-superusers can no longer issue <command>ALTER
       ROLE</>/<command>DATABASE SET</> for parameters that are not currently
       known to the server.  This allows the server to correctly check that
       superuser-only parameters are only set by superusers.  Previously,
       the <literal>SET</> would be allowed and then ignored at session start,
       making superuser-only custom parameters much less useful than they
       should be.
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

  </sect3>

  <sect3>
   <title>Queries</title>

   <itemizedlist>

    <listitem>
     <para>
      Perform <link linkend="SQL-FOR-UPDATE-SHARE"><command>SELECT
      FOR UPDATE</>/<literal>SHARE</></link> processing after
      applying <literal>LIMIT</>, so the number of rows returned
      is always predictable (Tom Lane)
     </para>

     <para>
      Previously, changes made by concurrent transactions could cause a
      <command>SELECT FOR UPDATE</> to unexpectedly return fewer rows than
      specified by its <literal>LIMIT</>. <literal>FOR UPDATE</> in combination
      with <literal>ORDER BY</> can still produce surprising results, but that
      can be corrected by placing <literal>FOR UPDATE</> in a subquery.
     </para>
    </listitem>

    <listitem>
     <para>
      Allow mixing of traditional and SQL-standard <link
      linkend="SQL-LIMIT"><literal>LIMIT</>/<literal>OFFSET</></link>
      syntax (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Extend the supported frame options in <link
      linkend="SQL-WINDOW">window functions</link> (Hitoshi
      Harada)
     </para>

     <para>
      Frames can now start with <literal>CURRENT ROW</>, and the <literal>ROWS
      <replaceable>n</> PRECEDING</>/<literal>FOLLOWING</> options are now
      supported.
     </para>
    </listitem>

    <listitem>
     <para>
      Make <command>SELECT INTO</> and <command>CREATE TABLE AS</> return
      row counts to the client in their command tags
      (Boszormenyi Zoltan)
     </para>

     <para>
      This can save an entire round-trip to the client, allowing result counts
      and pagination to be calculated without an additional
      <command>COUNT</command> query.
     </para>
    </listitem>

   </itemizedlist>

   <sect4>
    <title>Unicode Strings</title>

    <itemizedlist>

     <listitem>
      <para>
       Support Unicode surrogate pairs (dual 16-bit representation) in
       <link
       linkend="sql-syntax-strings-uescape"><literal>U&amp;</></link>
       strings and identifiers (Peter Eisentraut)
      </para>
     </listitem>

     <listitem>
      <para>
       Support Unicode escapes in <link
       linkend="sql-syntax-strings-escape"><literal>E'...'</></link>
       strings (Marko Kreen)
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

  </sect3>

  <sect3>
   <title>Object Manipulation</title>

   <itemizedlist>

    <listitem>
     <para>
      Speed up <link linkend="SQL-CREATEDATABASE"><command>CREATE
      DATABASE</></link> by deferring flushes to disk (Andres
      Freund, Greg Stark)
     </para>
    </listitem>

    <listitem>
     <para>
      Allow <link linkend="SQL-COMMENT">comments</link> on
      columns of tables, views, and composite types only, not other
      relation types such as indexes and <acronym>TOAST</> tables (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Allow the creation of <link
      linkend="SQL-CREATETYPE-enum">enumerated types</link> containing
      no values (Bruce Momjian)
     </para>
    </listitem>

    <listitem>
     <para>
      Let values of columns having storage type <literal>MAIN</> remain on
      the main heap page unless the row cannot fit on a page (Kevin Grittner)
     </para>

     <para>
      Previously <literal>MAIN</> values were forced out to <acronym>TOAST</>
      tables until the row size was less than one-quarter of the page size.
     </para>
    </listitem>

   </itemizedlist>

   <sect4>
    <title><command>ALTER TABLE</></title>

    <itemizedlist>

     <listitem>
      <para>
       Implement <literal>IF EXISTS</> for <literal>ALTER TABLE DROP COLUMN</>
       and <literal>ALTER TABLE DROP CONSTRAINT </> (Andres Freund)
      </para>
     </listitem>

     <listitem>
      <para>
       Allow <command>ALTER TABLE</> commands that rewrite tables to skip
       <acronym>WAL</> logging (Itagaki Takahiro)
      </para>

      <para>
       Such operations either produce a new copy of the table or are rolled
       back, so <acronym>WAL</> archiving can be skipped, unless running in
       continuous archiving mode.  This reduces I/O overhead and improves
       performance.
      </para>
     </listitem>

     <listitem>
      <para>
       Fix failure of <literal>ALTER TABLE <replaceable>table</> ADD COLUMN
       <replaceable>col</> serial</literal> when done by non-owner of table
       (Tom Lane)
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

   <sect4>
    <title><link linkend="SQL-CREATETABLE"><command>CREATE TABLE</></link></title>

    <itemizedlist>

     <listitem>
      <para>
       Add support for copying <literal>COMMENTS</> and <literal>STORAGE</>
       settings in <command>CREATE TABLE ... LIKE</> commands
       (Itagaki Takahiro)
      </para>
     </listitem>

     <listitem>
      <para>
       Add a shortcut for copying all properties in <command>CREATE
       TABLE ... LIKE</> commands (Itagaki Takahiro)
      </para>
     </listitem>

     <listitem>
      <para>
       Add the SQL-standard
       <literal>CREATE TABLE ... OF <replaceable>type</></literal> command
       (Peter Eisentraut)
      </para>

      <para>
       This allows creation of a table that matches an existing composite
       type. Additional constraints and defaults can be specified in the
       command.
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

   <sect4>
    <title>Constraints</title>

    <itemizedlist>

     <listitem>
      <para>
       Add <link linkend="SQL-CREATETABLE-compatibility">deferrable
       unique constraints</link> (Dean Rasheed)
      </para>

      <para>
       This allows mass updates, such as
       <literal>UPDATE tab SET col = col + 1</>,
       to work reliably
       on columns that have unique indexes or are marked as primary keys.
       If the constraint is specified as <literal>DEFERRABLE</> it will be
       checked at the end of the statement, rather than after each row is
       updated. The constraint check can also be deferred until the end of the
       current transaction, allowing such updates to be spread over multiple
       SQL commands.
      </para>
     </listitem>

     <listitem>
      <para>
       Add
       <link linkend="ddl-constraints-exclusion">exclusion constraints</link>
       (Jeff Davis)
      </para>

      <para>
       Exclusion constraints generalize uniqueness constraints by allowing
       arbitrary comparison operators, not just equality.  They are created
       with the <link linkend="SQL-CREATETABLE-EXCLUDE"><command>CREATE
       TABLE CONSTRAINT ... EXCLUDE</></link> clause.
       The most common use of exclusion constraints is to specify that column
       entries must not overlap, rather than simply not be equal.  This is
       useful for time periods and other ranges, as well as arrays.
       This feature enhances checking of data integrity for many
       calendaring, time-management, and scientific applications.
      </para>
     </listitem>

     <listitem>
      <para>
       Improve uniqueness-constraint violation error messages to
       report the values causing the failure (Itagaki Takahiro)
      </para>

      <para>
       For example, a uniqueness constraint violation might now report
       <literal>Key (x)=(2) already exists</>.
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

   <sect4>
    <title>Object Permissions</title>

    <itemizedlist>

     <listitem>
      <para>
       Add the ability to make mass permission changes across a whole
       schema using the new <link
       linkend="SQL-GRANT"><command>GRANT</>/<command>REVOKE
       IN SCHEMA</></link> clause (Petr Jelinek)
      </para>

      <para>
       This simplifies management of object permissions
       and makes it easier to utilize database roles for application
       data security.
      </para>
     </listitem>

     <listitem>
      <para>
       Add <link linkend="SQL-ALTERDEFAULTPRIVILEGES"><command>ALTER
       DEFAULT PRIVILEGES</></link> command to control privileges
       of objects created later (Petr Jelinek)
      </para>

      <para>
       This greatly simplifies the assignment of object privileges in a
       complex database application.  Default privileges can be set for
       tables, views, sequences, and functions. Defaults may be assigned on a
       per-schema basis, or database-wide.
      </para>
     </listitem>

     <listitem>
      <para>
       Add the ability to control large object (BLOB) permissions with
       <command>GRANT</>/<command>REVOKE</> (KaiGai Kohei)
      </para>

      <para>
       Formerly, any database user could read or modify any large object.
       Read and write permissions can now be granted and revoked per
       large object, and the ownership of large objects is tracked.
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

  </sect3>

  <sect3>
   <title>Utility Operations</title>

   <itemizedlist>

    <listitem>
     <para>
      Make <link linkend="SQL-LISTEN"><command>LISTEN</></link>/<link
      linkend="SQL-NOTIFY"><command>NOTIFY</></link> store pending events
      in a memory queue, rather than in a system table (Joachim
      Wieland)
     </para>

     <para>
      This substantially improves performance, while retaining the existing
      features of transactional support and guaranteed delivery.
     </para>
    </listitem>

    <listitem>
     <para>
      Allow <link linkend="SQL-NOTIFY"><command>NOTIFY</></link>
      to pass an optional <quote>payload</> string to listeners
      (Joachim Wieland)
     </para>

     <para>
      This greatly improves the usefulness of
      <command>LISTEN</>/<command>NOTIFY</> as a
      general-purpose event queue system.
     </para>
    </listitem>

    <listitem>
     <para>
      Allow <link linkend="SQL-CLUSTER"><command>CLUSTER</></link>
      on all per-database system catalogs (Tom Lane)
     </para>

     <para>
      Shared catalogs still cannot be clustered.
     </para>
    </listitem>

   </itemizedlist>

   <sect4>
    <title><link linkend="SQL-COPY"><command>COPY</></link></title>

    <itemizedlist>

     <listitem>
      <para>
       Accept <literal>COPY ... CSV FORCE QUOTE *</>
       (Itagaki Takahiro)
      </para>

      <para>
       Now <literal>*</> can be used as shorthand for <quote>all columns</>
       in the <literal>FORCE QUOTE</> clause.
      </para>
     </listitem>

     <listitem>
      <para>
       Add new <command>COPY</> syntax that allows options to be
       specified inside parentheses (Robert Haas, Emmanuel Cecchet)
      </para>

      <para>
       This allows greater flexibility for future <command>COPY</> options.
       The old syntax is still supported, but only for pre-existing options.
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

   <sect4>
    <title><link linkend="SQL-EXPLAIN"><command>EXPLAIN</></link></title>

    <itemizedlist>

     <listitem>
      <para>
       Allow <command>EXPLAIN</> to output in <acronym>XML</>,
       <acronym>JSON</>, or <acronym>YAML</> format (Robert Haas, Greg
       Sabino Mullane)
      </para>

      <para>
       The new output formats are easily machine-readable, supporting the
       development of new tools for analysis of <command>EXPLAIN</> output.
      </para>
     </listitem>

     <listitem>
      <para>
       Add new <literal>BUFFERS</> option to report query
       buffer usage during <command>EXPLAIN ANALYZE</> (Itagaki Takahiro)
      </para>

      <para>
       This allows better query profiling for individual queries.
       Buffer usage is no longer reported in the output for <link
       linkend="runtime-config-statistics-monitor">log_statement_stats</link>
       and related settings.
      </para>
     </listitem>

     <listitem>
      <para>
       Add hash usage information to <command>EXPLAIN</> output (Robert
       Haas)
      </para>
     </listitem>

     <listitem>
      <para>
       Add new <command>EXPLAIN</> syntax that allows options to be
       specified inside parentheses (Robert Haas)
      </para>

      <para>
       This allows greater flexibility for future <command>EXPLAIN</> options.
       The old syntax is still supported, but only for pre-existing options.
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

   <sect4>
    <title><link linkend="SQL-VACUUM"><command>VACUUM</></link></title>

    <itemizedlist>

     <listitem>
      <para>
       Change <command>VACUUM FULL</> to rewrite the entire table and
       rebuild its indexes, rather than moving individual rows around to
       compact space (Itagaki Takahiro, Tom Lane)
      </para>

      <para>
       The previous method was usually slower and caused index bloat.
       Note that the new method will use more disk space transiently
       during <command>VACUUM FULL</>; potentially as much as twice
       the space normally occupied by the table and its indexes.
      </para>

     </listitem>

     <listitem>
      <para>
       Add new <command>VACUUM</> syntax that allows options to be
       specified inside parentheses (Itagaki Takahiro)
      </para>

      <para>
       This allows greater flexibility for future <command>VACUUM</> options.
       The old syntax is still supported, but only for pre-existing options.
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

   <sect4>
    <title>Indexes</title>

    <itemizedlist>

     <listitem>
      <para>
       Allow an index to be named automatically by omitting the index name in
       <link linkend="SQL-CREATEINDEX"><command>CREATE INDEX</></link>
       (Tom Lane)
      </para>
     </listitem>

     <listitem>
      <para>
       By default, multicolumn indexes are now named after all their columns;
       and index expression columns are now named based on their expressions
       (Tom Lane)
      </para>
     </listitem>

     <listitem>
      <para>
       Reindexing shared system catalogs is now fully transactional
       and crash-safe (Tom Lane)
      </para>

      <para>
       Formerly, reindexing a shared index was only allowed in standalone
       mode, and a crash during the operation could leave the index in
       worse condition than it was before.
      </para>
     </listitem>

     <listitem>
      <para>
       Add <literal>point_ops</> operator class for <acronym>GiST</>
      (Teodor Sigaev)
      </para>

      <para>
       This feature permits <acronym>GiST</> indexing of <type>point</>
       columns.  The index can be used for several types of queries
       such as <replaceable>point</> <literal>&lt;@</> <replaceable>polygon</>
       (point is in polygon).  This should make many
       <productname>PostGIS</> queries faster.
      </para>
     </listitem>

     <listitem>
      <para>
       Use red-black binary trees for <acronym>GIN</> index creation
       (Teodor Sigaev)
      </para>

      <para>
       Red-black trees are self-balancing.  This avoids slowdowns in
       cases where the input is in nonrandom order.
      </para>

     </listitem>

    </itemizedlist>

   </sect4>

  </sect3>

  <sect3>
   <title>Data Types</title>

   <itemizedlist>

    <listitem>
     <para>
      Allow <link linkend="datatype-binary"><type>bytea</></link> values
      to be written in hex notation (Peter Eisentraut)
     </para>

     <para>
      The server parameter <link
      linkend="guc-bytea-output"><varname>bytea_output</></link> controls
      whether hex or traditional format is used for <type>bytea</>
      output.  Libpq's <function>PQescapeByteaConn()</> function automatically
      uses the hex format when connected to <productname>PostgreSQL</> 9.0
      or newer servers.  However, pre-9.0 libpq versions will not
      correctly process hex format from newer servers.
     </para>

     <para>
      The new hex format will be directly compatible with more applications
      that use binary data, allowing them to store and retrieve it without
      extra conversion.  It is also significantly faster to read and write
      than the traditional format.
     </para>
    </listitem>

    <listitem>
     <para>
      Allow server parameter <link
      linkend="guc-extra-float-digits">extra_float_digits</link>
      to be increased to <literal>3</> (Tom Lane)
     </para>

     <para>
      The previous maximum <varname>extra_float_digits</> setting was
      <literal>2</>.  There are cases where 3 digits are needed to dump and
      restore <type>float4</> values exactly.  <application>pg_dump</> will
      now use the setting of 3 when dumping from a server that allows it.
     </para>
    </listitem>

    <listitem>
     <para>
      Tighten input checking for <type>int2vector</> values (Caleb
      Welton)
     </para>
    </listitem>

   </itemizedlist>

   <sect4>
    <title><link linkend="textsearch">Full Text Search</link></title>

    <itemizedlist>

     <listitem>
      <para>
       Add prefix support in <literal>synonym</> dictionaries
       (Teodor Sigaev)
      </para>
     </listitem>

     <listitem>
      <para>
       Add <firstterm>filtering</> dictionaries (Teodor Sigaev)
      </para>

      <para>
       Filtering dictionaries allow tokens to be modified then passed to
       subsequent dictionaries.
      </para>
     </listitem>

     <listitem>
      <para>
       Allow underscores in email-address tokens (Teodor Sigaev)
      </para>
     </listitem>

     <listitem>
      <para>
       Use more standards-compliant rules for parsing <acronym>URL</> tokens
       (Tom Lane)
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

  </sect3>

  <sect3>
   <title>Functions</title>

   <itemizedlist>

    <listitem>
     <para>
      Allow function calls to supply parameter names and match them to named
      parameters in the function definition (Pavel Stehule)
     </para>

     <para>
      For example, if a function is defined to take parameters <literal>a</>
      and <literal>b</>, it can be called with <literal>func(a := 7, b
      := 12)</> or <literal>func(b := 12, a := 7)</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Support locale-specific <link
      linkend="functions-posix-regexp">regular expression</link>
      processing with <acronym>UTF-8</> server encoding (Tom Lane)
     </para>

     <para>
      Locale-specific regular expression functionality includes
      case-insensitive matching and locale-specific character classes.
      Previously, these features worked correctly for non-<acronym>ASCII</>
      characters only if the database used a single-byte server encoding (such
      as LATIN1).  They will still misbehave in multi-byte encodings other
      than <acronym>UTF-8</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Add support for scientific notation in <link
      linkend="functions-formatting"><function>to_char()</></link>
      (<link linkend="functions-formatting-numeric-table"><literal>EEEE</>
      specification</link>)
      (Pavel Stehule, Brendan Jurd)
     </para>
    </listitem>

    <listitem>
     <para>
      Make <function>to_char()</> honor <link
      linkend="functions-formatting-datetimemod-table"><literal>FM</></link>
      (fill mode) in <literal>Y</>, <literal>YY</>, and
      <literal>YYY</> specifications (Bruce Momjian, Tom Lane)
     </para>

     <para>
      It was already honored by <literal>YYYY</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <function>to_char()</> to output localized numeric and monetary
      strings in the correct encoding on <productname>Windows</>
      (Hiroshi Inoue, Itagaki Takahiro, Bruce Momjian)
     </para>
    </listitem>

    <listitem>
     <para>
      Correct calculations of <link
      linkend="functions-geometry-op-table"><quote>overlaps</quote></link>
      and <quote>contains</quote> operations for polygons (Teodor Sigaev)
     </para>

     <para>
      The polygon <literal>&amp;&amp;</> (overlaps) operator formerly just
      checked to see if the two polygons' bounding boxes overlapped.  It now
      does a more correct check.  The polygon <literal>@&gt;</> and
      <literal>&lt;@</> (contains/contained by) operators formerly checked
      to see if one polygon's vertexes were all contained in the other;
      this can wrongly report <quote>true</> for some non-convex polygons.
      Now they check that all line segments of one polygon are contained in
      the other.
     </para>
    </listitem>

   </itemizedlist>

   <sect4>
    <title>Aggregates</title>

    <itemizedlist>

     <listitem>
      <para>
       Allow aggregate functions to use <link
       linkend="syntax-aggregates"><literal>ORDER BY</></link> (Andrew Gierth)
      </para>

      <para>
       For example, this is now supported: <literal>array_agg(a ORDER BY
       b)</>.  This is useful with aggregates for which the order of input
       values is significant, and eliminates the need to use a nonstandard
       subquery to determine the ordering.
      </para>
     </listitem>

     <listitem>
      <para>
       Multi-argument aggregate functions can now use <literal>DISTINCT</>
       (Andrew Gierth)
      </para>
     </listitem>

     <listitem>
      <para>
       Add the <link
       linkend="functions-aggregate-table"><function>string_agg()</></link>
       aggregate function to combine values into a single
       string (Pavel Stehule)
      </para>
     </listitem>

     <listitem>
      <para>
       Aggregate functions that are called with <literal>DISTINCT</> are
       now passed NULL values if the aggregate transition function is
       not marked as <literal>STRICT</> (Andrew Gierth)
      </para>

      <para>
       For example, <literal>agg(DISTINCT x)</> might pass a NULL <literal>x</>
       value to <function>agg()</>.  This is more consistent with the behavior
       in non-<literal>DISTINCT</> cases.
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

   <sect4>
    <title>Bit Strings</title>

    <itemizedlist>

     <listitem>
      <para>
       Add <link
       linkend="functions-binarystring-other"><function>get_bit()</></link>
       and <function>set_bit()</> functions for <type>bit</>
       strings, mirroring those for <type>bytea</> (Leonardo
       F)
      </para>
     </listitem>

     <listitem>
      <para>
       Implement <link
       linkend="functions-string-sql"><function>OVERLAY()</></link>
       (replace) for <type>bit</> strings and <type>bytea</>
       (Leonardo F)
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

   <sect4>
    <title>Object Information Functions</title>

    <itemizedlist>

     <listitem>
      <para>
       Add <link
       linkend="functions-admin-dbsize"><function>pg_table_size()</></link>
       and <function>pg_indexes_size()</> to provide a more
       user-friendly interface to the <function>pg_relation_size()</>
       function (Bernd Helmle)
      </para>
     </listitem>

     <listitem>
      <para>
       Add <link
       linkend="functions-info-access-table"><function>has_sequence_privilege()</></link>
       for sequence permission checking (Abhijit Menon-Sen)
      </para>
     </listitem>

     <listitem>
      <para>
       Update the <link linkend="information-schema">information_schema</link>
       views to conform to SQL:2008
       (Peter Eisentraut)
      </para>
     </listitem>

     <listitem>
      <para>
       Make the <literal>information_schema</> views correctly display maximum
       octet lengths for <type>char</> and <type>varchar</> columns (Peter
       Eisentraut)
      </para>
     </listitem>

     <listitem>
      <para>
       Speed up <literal>information_schema</> privilege views
       (Joachim Wieland)
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

   <sect4>
    <title>Function and Trigger Creation</title>

    <itemizedlist>

     <listitem>
      <para>
       Support execution of anonymous code blocks using the <link
       linkend="SQL-DO"><command>DO</></link> statement
       (Petr Jelinek, Joshua Tolley, Hannu Valtonen)
      </para>

      <para>
       This allows execution of server-side code without the need to create
       and delete a temporary function definition.  Code can be executed in
       any language for which the user has permissions to define a function.
      </para>
     </listitem>

     <listitem>
      <para>
       Implement SQL-standard-compliant <link
       linkend="SQL-CREATETRIGGER">per-column triggers</link>
       (Itagaki Takahiro)
      </para>

      <para>
       Such triggers are fired only when the specified column(s) are affected
       by the query, e.g. appear in an <command>UPDATE</>'s <literal>SET</>
       list.
      </para>
     </listitem>

     <listitem>
      <para>
       Add the <literal>WHEN</> clause to <link
       linkend="SQL-CREATETRIGGER"><command>CREATE TRIGGER</></link>
       to allow control over whether a trigger is fired (Itagaki
       Takahiro)
      </para>

      <para>
       While the same type of check can always be performed inside the
       trigger, doing it in an external <literal>WHEN</> clause can have
       performance benefits.
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

  </sect3>

  <sect3>
   <title>Server-Side Languages</title>

   <itemizedlist>

    <listitem>
     <para>
      Add the <literal>OR REPLACE</> clause to <link
      linkend="SQL-CREATELANGUAGE"><command>CREATE LANGUAGE</></link>
      (Tom Lane)
     </para>

     <para>
      This is helpful to optionally install a language if it does not
      already exist, and is particularly helpful now that PL/pgSQL is
      installed by default.
     </para>
    </listitem>

    </itemizedlist>

    <sect4>
    <title><link linkend="plpgsql">PL/pgSQL</link> Server-Side
    Language</title>

    <itemizedlist>

     <listitem>
      <para>
       Install PL/pgSQL by default (Bruce Momjian)
      </para>

      <para>
       The language can still be removed from a particular database if the
       administrator has security or performance concerns about making it
       available.
      </para>
     </listitem>

     <listitem>
      <para>
       Improve handling of cases where PL/pgSQL variable names conflict with
       identifiers used in queries within a function
       (Tom Lane)
      </para>

      <para>
       The default behavior is now to throw an error when there is a conflict,
       so as to avoid surprising behaviors.  This can be modified, via the
       configuration parameter <link
       linkend="plpgsql-var-subst"><varname>plpgsql.variable_conflict</></link>
       or the per-function option <literal>#variable_conflict</>, to allow
       either the variable or the query-supplied column to be used.  In any
       case PL/pgSQL will no longer attempt to substitute variables in places
       where they would not be syntactically valid.
      </para>
     </listitem>

     <listitem>
      <para>
       Make PL/pgSQL use the main lexer, rather than its own version
       (Tom Lane)
      </para>

      <para>
       This ensures accurate tracking of the main system's behavior for details
       such as string escaping.  Some user-visible details, such as the set
       of keywords considered reserved in PL/pgSQL, have changed in
       consequence.
      </para>
     </listitem>

     <listitem>
      <para>
       Avoid throwing an unnecessary error for an invalid record reference
       (Tom Lane)
      </para>

      <para>
       An error is now thrown only if the reference is actually fetched,
       rather than whenever the enclosing expression is reached.  For
       example, many people have tried to do this in triggers:
<programlisting>
if TG_OP = 'INSERT' and NEW.col1 = ... then
</programlisting>
       This will now actually work as expected.
      </para>
     </listitem>

     <listitem>
      <para>
       Improve PL/pgSQL's ability to handle row types with dropped columns
       (Pavel Stehule)
      </para>
     </listitem>

     <listitem>
      <para>
       Allow input parameters to be assigned values within
       PL/pgSQL functions (Steve Prentice)
      </para>

      <para>
       Formerly, input parameters were treated as being declared
       <literal>CONST</>, so the function's code could not change their
       values.  This restriction has been removed to simplify
       porting of functions from other DBMSes that do not impose the
       equivalent restriction.  An input parameter now acts like a local
       variable initialized to the passed-in value.
      </para>
     </listitem>

     <listitem>
      <para>
       Improve error location reporting in PL/pgSQL (Tom Lane)
      </para>
     </listitem>

     <listitem>
      <para>
       Add <replaceable>count</> and <literal>ALL</> options to <command>MOVE
       FORWARD</>/<literal>BACKWARD</> in PL/pgSQL (Pavel Stehule)
      </para>
     </listitem>

     <listitem>
      <para>
       Allow PL/pgSQL's <literal>WHERE CURRENT OF</> to use a cursor
       variable (Tom Lane)
      </para>
     </listitem>

     <listitem>
      <para>
       Allow PL/pgSQL's <command>OPEN <replaceable>cursor</> FOR EXECUTE</> to
       use parameters (Pavel Stehule, Itagaki Takahiro)
      </para>

      <para>
       This is accomplished with a new <literal>USING</> clause.
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

   <sect4>
    <title><link linkend="plperl">PL/Perl</link> Server-Side Language</title>

    <itemizedlist>

     <listitem>
      <para>
       Add new PL/Perl functions: <link
       linkend="plperl-utility-functions"><function>quote_literal()</></link>,
       <function>quote_nullable()</>, <function>quote_ident()</>,
       <function>encode_bytea()</>, <function>decode_bytea()</>,
       <function>looks_like_number()</>,
       <function>encode_array_literal()</>,
       <function>encode_array_constructor()</> (Tim Bunce)
      </para>
     </listitem>

     <listitem>
      <para>
       Add server parameter <link
       linkend="guc-plperl-on-init"><varname>plperl.on_init</></link> to
       specify a PL/Perl initialization function (Tim
       Bunce)
      </para>

      <para>
       <link
       linkend="guc-plperl-on-plperl-init"><varname>plperl.on_plperl_init</></link>
       and <link
       linkend="guc-plperl-on-plperl-init"><varname>plperl.on_plperlu_init</></link>
       are also available for initialization that is specific to the trusted
       or untrusted language respectively.
      </para>
     </listitem>

     <listitem>
      <para>
       Support <command>END</> blocks in PL/Perl (Tim Bunce)
      </para>

      <para>
       <command>END</> blocks do not currently allow database access.
      </para>
     </listitem>

     <listitem>
      <para>
       Allow <command>use strict</> in PL/Perl (Tim Bunce)
      </para>

      <para>
       Perl <literal>strict</> checks can also be globally enabled with the
       new server parameter <link
       linkend="guc-plperl-use-strict"><varname>plperl.use_strict</></link>.
      </para>
     </listitem>

     <listitem>
      <para>
       Allow <command>require</> in PL/Perl (Tim Bunce)
      </para>

      <para>
       This basically tests to see if the module is loaded, and if not,
       generates an error.  It will not allow loading of modules that
       the administrator has not preloaded via the initialization parameters.
      </para>
     </listitem>

     <listitem>
      <para>
       Allow <command>use feature</> in PL/Perl if Perl version 5.10 or
       later is used (Tim Bunce)
      </para>
     </listitem>

     <listitem>
      <para>
       Verify that PL/Perl return values are valid in the server encoding
       (Andrew Dunstan)
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

   <sect4>
    <title><link linkend="plpython">PL/Python</link> Server-Side Language</title>

    <itemizedlist>

     <listitem>
      <para>
       Add Unicode support in PL/Python (Peter Eisentraut)
      </para>

      <para>
       Strings are automatically converted from/to the server encoding as
       necessary.
      </para>
     </listitem>

     <listitem>
      <para>
       Improve <type>bytea</> support in PL/Python (Caleb Welton)
      </para>

      <para>
       <type>Bytea</> values passed into PL/Python are now represented as
       binary, rather than the PostgreSQL <type>bytea</> text format.
       <type>Bytea</> values containing null bytes are now also output
       properly from PL/Python.  Passing of boolean, integer, and float
       values was also improved.
      </para>
     </listitem>

     <listitem>
      <para>
       Support <link linkend="plpython-arrays">arrays</link> as parameters and
       return values in PL/Python (Peter Eisentraut)
      </para>
     </listitem>

     <listitem>
      <para>
       Improve mapping of SQL domains to Python types (Peter Eisentraut)
      </para>
     </listitem>

     <listitem>
      <para>
       Add <application>Python</> 3 support to PL/Python (Peter Eisentraut)
      </para>

      <para>
       The new server-side language is called <link
       linkend="plpython-python23"><literal>plpython3u</></link>.  This
       cannot be used in the same session with the
       <application>Python</> 2 server-side language.
      </para>
     </listitem>

     <listitem>
      <para>
       Improve error location and exception reporting in PL/Python (Peter Eisentraut)
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

  </sect3>

  <sect3>
   <title>Client Applications</title>

   <itemizedlist>

    <listitem>
    <para>
     Add an <option>--analyze-only</> option to <link
     linkend="APP-VACUUMDB"><command>vacuumdb</></link>, to analyze without
     vacuuming (Bruce Momjian)
     </para>
    </listitem>

   </itemizedlist>

   <sect4>
    <title><link linkend="APP-PSQL"><application>psql</></link></title>

    <itemizedlist>

     <listitem>
      <para>
       Add support for quoting/escaping the values of <application>psql</>
       <link linkend="APP-PSQL-variables">variables</link> as SQL strings or
       identifiers (Pavel Stehule, Robert Haas)
      </para>

      <para>
       For example, <literal>:'var'</> will produce the value of
       <literal>var</> quoted and properly escaped as a literal string, while
       <literal>:"var"</> will produce its value quoted and escaped as an
       identifier.
      </para>
     </listitem>

     <listitem>
      <para>
       Ignore a leading UTF-8-encoded Unicode byte-order marker in
       script files read by <application>psql</> (Itagaki Takahiro)
      </para>

      <para>
       This is enabled when the client encoding is <acronym>UTF-8</>.
       It improves compatibility with certain editors, mostly on Windows,
       that insist on inserting such markers.
      </para>
     </listitem>

     <listitem>
      <para>
       Fix <command>psql --file -</> to properly honor <link
       linkend="R1-APP-PSQL-3"><option>--single-transaction</></link>
       (Bruce Momjian)
      </para>
     </listitem>

     <listitem>
      <para>
       Avoid overwriting of <application>psql</>'s command-line history when
       two <application>psql</> sessions are run concurrently (Tom Lane)
      </para>
     </listitem>

     <listitem>
      <para>
       Improve <application>psql</>'s tab completion support (Itagaki
       Takahiro)
      </para>
     </listitem>

     <listitem>
      <para>
       Show <literal>\timing</> output when it is enabled, regardless of
       <quote>quiet</> mode (Peter Eisentraut)
      </para>
     </listitem>

    </itemizedlist>

    <sect5>
    <title><application>psql</> Display</title>

     <itemizedlist>

      <listitem>
       <para>
        Improve display of wrapped columns in <application>psql</> (Roger
        Leigh)
       </para>

       <para>
        This behavior is now the default.
        The previous formatting is available by using <command>\pset linestyle
        old-ascii</>.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <application>psql</> to use fancy Unicode line-drawing
        characters via <command>\pset linestyle unicode</> (Roger Leigh)
       </para>
      </listitem>

     </itemizedlist>

    </sect5>

    <sect5>
     <title><application>psql</> <link
     linkend="APP-PSQL-meta-commands"><command>\d</></link>
     Commands</title>

     <itemizedlist>

      <listitem>
       <para>
        Make <command>\d</> show child tables that inherit from the specified
        parent (Damien Clochard)
       </para>

       <para>
        <command>\d</> shows only the number of child tables, while
        <command>\d+</> shows the names of all child tables.
       </para>
      </listitem>

      <listitem>
       <para>
        Show definitions of index columns in <command>\d index_name</>
        (Khee Chin)
       </para>

       <para>
        The definition is useful for expression indexes.
       </para>
      </listitem>

      <listitem>
       <para>
        Show a view's defining query only in
        <command>\d+</>, not in <command>\d</> (Peter Eisentraut)
       </para>

       <para>
        Always including the query was deemed overly verbose.
       </para>
      </listitem>

     </itemizedlist>

    </sect5>
   </sect4>

   <sect4>
    <title><link linkend="APP-PGDUMP"><application>pg_dump</></link></title>

    <itemizedlist>

     <listitem>
      <para>
       Make <application>pg_dump</>/<application>pg_restore</>
       <link linkend="pg-dump-options"><option>--clean</></link>
       also remove large objects (Itagaki Takahiro)
      </para>
     </listitem>

     <listitem>
      <para>
       Fix <application>pg_dump</> to properly dump large objects when
       <literal>standard_conforming_strings</> is enabled (Tom Lane)
      </para>

      <para>
       The previous coding could fail when dumping to an archive file
       and then generating script output from <application>pg_restore</>.
      </para>
     </listitem>

     <listitem>
      <para>
       <application>pg_restore</> now emits large-object data in hex format
       when generating script output (Tom Lane)
      </para>

      <para>
       This could cause compatibility problems if the script is then
       loaded into a pre-9.0 server.  To work around that, restore
       directly to the server, instead.
      </para>
     </listitem>

     <listitem>
      <para>
       Allow <application>pg_dump</> to dump comments attached to columns
       of composite types (Taro Minowa (Higepon))
      </para>
     </listitem>

     <listitem>
      <para>
       Make <application>pg_dump</> <link
       linkend="pg-dump-options"><option>--verbose</></link>
       output the <application>pg_dump</> and server versions
       in text output mode (Jim Cox, Tom Lane)
      </para>

      <para>
       These were already provided in custom output mode.
      </para>
     </listitem>

     <listitem>
      <para>
       <application>pg_restore</> now complains if any command-line arguments
       remain after the switches and optional file name (Tom Lane)
      </para>

      <para>
       Previously, it silently ignored any such arguments.
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

   <sect4>
    <title><link
    linkend="app-pg-ctl"><application>pg_ctl</></link></title>

    <itemizedlist>

     <listitem>
      <para>
       Allow <application>pg_ctl</> to be used safely to start the
       <application>postmaster</> during a system reboot (Tom Lane)
      </para>

      <para>
       Previously, <application>pg_ctl</>'s parent process could have been
       mistakenly identified as a running <application>postmaster</> based on
       a stale <application>postmaster</> lock file, resulting in a transient
       failure to start the database.
      </para>
     </listitem>

     <listitem>
      <para>
       Give <application>pg_ctl</> the ability to initialize the database
       (by invoking <application>initdb</>) (Zdenek Kotala)
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

  </sect3>

  <sect3>
   <title><application>Development Tools</></title>

   <sect4>
    <title><link linkend="libpq"><application>libpq</></link></title>

    <itemizedlist>

     <listitem>
      <para>
       Add new <application>libpq</> functions
       <link
       linkend="libpq-connect"><function>PQconnectdbParams()</></link>
       and <function>PQconnectStartParams()</> (Guillaume
       Lelarge)
      </para>

      <para>
       These functions are similar to <function>PQconnectdb()</> and
       <function>PQconnectStart()</> except that they accept a null-terminated
       array of connection options, rather than requiring all options to
       be provided in a single string.
      </para>
     </listitem>

     <listitem>
      <para>
       Add <application>libpq</> functions <link
       linkend="libpq-exec-escape-string"><function>PQescapeLiteral()</></link>
       and <function>PQescapeIdentifier()</> (Robert Haas)
      </para>

      <para>
       These functions return appropriately quoted and escaped SQL string
       literals and identifiers. The caller is not required to pre-allocate
       the string result, as is required by <function>PQescapeStringConn()</>.
      </para>
     </listitem>

     <listitem>
      <para>
       Add support for a per-user service file (<link
       linkend="libpq-pgservice"><filename>.pg_service.conf</></link>),
       which is checked before the site-wide service file
       (Peter Eisentraut)
      </para>
     </listitem>

     <listitem>
      <para>
       Properly report an error if the specified <application>libpq</> service
       cannot be found (Peter Eisentraut)
      </para>
     </listitem>

     <listitem>
      <para>
       Add <link linkend="libpq-keepalives">TCP keepalive settings</link>
       in libpq (Tollef Fog Heen, Fujii Masao, Robert Haas)
      </para>

      <para>
       Keepalive settings were already supported on the server end of
       TCP connections.
      </para>
     </listitem>

     <listitem>
      <para>
       Avoid extra system calls to block and unblock <literal>SIGPIPE</>
       in <application>libpq</>, on platforms that offer alternative methods
       (Jeremy Kerr)
      </para>
     </listitem>

     <listitem>
      <para>
       When a <link linkend="libpq-pgpass"><filename>.pgpass</></link>-supplied
       password fails, mention where the password came from in the error
       message (Bruce Momjian)
      </para>
     </listitem>

     <listitem>
      <para>
       Load all SSL certificates given in the client certificate file
       (Tom Lane)
      </para>

      <para>
       This improves support for indirectly-signed SSL certificates.
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

   <sect4>
    <title><link linkend="ecpg"><application>ecpg</></link></title>

    <itemizedlist>

     <listitem>
      <para>
       Add <link linkend="ecpg-descriptors"><acronym>SQLDA</></link>
       (SQL Descriptor Area) support to <application>ecpg</>
       (Boszormenyi Zoltan)
      </para>
     </listitem>

     <listitem>
      <para>
       Add the <link linkend="ecpg-descriptors"><command>DESCRIBE</>
       [ <literal>OUTPUT</> ]</link> statement to <application>ecpg</>
       (Boszormenyi Zoltan)
      </para>
     </listitem>

     <listitem>
      <para>
       Add an <link linkend="ecpg-library">ECPGtransactionStatus</link>
       function to return the current transaction status (Bernd Helmle)
      </para>
     </listitem>

     <listitem>
      <para>
       Add the <literal>string</> data type in <application>ecpg</>
       Informix-compatibility mode (Boszormenyi Zoltan)
      </para>
     </listitem>

     <listitem>
      <para>
       Allow <application>ecpg</> to use <literal>new</> and <literal>old</>
       variable names without restriction (Michael Meskes)
      </para>
     </listitem>

     <listitem>
      <para>
       Allow <application>ecpg</> to use variable names in
       <function>free()</> (Michael Meskes)
      </para>
     </listitem>

     <listitem>
      <para>
       Make <function>ecpg_dynamic_type()</> return zero for non-SQL3 data
       types (Michael Meskes)
      </para>

      <para>
       Previously it returned the negative of the data type OID.
       This could be confused with valid type OIDs, however.
      </para>
     </listitem>

     <listitem>
      <para>
       Support <type>long long</> types on platforms that already have 64-bit
       <type>long</> (Michael Meskes)
      </para>
     </listitem>

     </itemizedlist>

     <sect5>
      <title><application>ecpg</> Cursors</title>

      <itemizedlist>

      <listitem>
       <para>
        Add out-of-scope cursor support in <application>ecpg</>'s native mode
        (Boszormenyi Zoltan)
       </para>

       <para>
        This allows <command>DECLARE</> to use variables that are not in
        scope when <command>OPEN</> is called. This facility already existed
        in <application>ecpg</>'s Informix-compatibility mode.
       </para>
      </listitem>

      <listitem>
       <para>
        Allow dynamic cursor names in <application>ecpg</> (Boszormenyi Zoltan)
       </para>
      </listitem>

      <listitem>
       <para>
        Allow <application>ecpg</> to use noise words <literal>FROM</> and
        <literal>IN</> in <command>FETCH</> and <command>MOVE</> (Boszormenyi
        Zoltan)
       </para>
      </listitem>

     </itemizedlist>

    </sect5>

   </sect4>

  </sect3>

  <sect3>
   <title>Build Options</title>

   <itemizedlist>

    <listitem>
     <para>
      Enable client thread safety by default (Bruce Momjian)
     </para>

     <para>
      The thread-safety option can be disabled with <link
      linkend="configure"><literal>configure</></link>
      <option>--disable-thread-safety</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Add support for controlling the Linux out-of-memory killer
      (Alex Hunsaker, Tom Lane)
     </para>

     <para>
      Now that <filename>/proc/self/oom_adj</> allows disabling
      of the <productname>Linux</> out-of-memory (<acronym>OOM</>)
      killer, it's recommendable to disable OOM kills for the postmaster.
      It may then be desirable to re-enable OOM kills for the postmaster's
      child processes.  The new compile-time option <link
      linkend="linux-memory-overcommit"><literal>LINUX_OOM_ADJ</></link>
      allows the killer to be reactivated for child processes.
     </para>
    </listitem>

   </itemizedlist>

   <sect4>
    <title>Makefiles</title>

    <itemizedlist>

     <listitem>
      <para>
       New <filename>Makefile</> targets <link
       linkend="build"><literal>world</></link>,
       <literal>install-world</>, and <literal>installcheck-world</>
       (Andrew Dunstan)
      </para>

      <para>
       These are similar to the existing <literal>all</>, <literal>install</>,
       and <literal>installcheck</> targets, but they also build the
       <acronym>HTML</> documentation, build and test <filename>contrib</>,
       and test server-side languages and <application>ecpg</>.
      </para>
     </listitem>

     <listitem>
      <para>
       Add data and documentation installation location control to
       <acronym>PGXS</> Makefiles (Mark Cave-Ayland)
      </para>
     </listitem>

    <listitem>
     <para>
      Add Makefile rules to build the <productname>PostgreSQL</> documentation
      as a single <acronym>HTML</> file or as a single plain-text file
      (Peter Eisentraut, Bruce Momjian)
     </para>
    </listitem>

    </itemizedlist>

   </sect4>

   <sect4>
    <title>Windows</title>

    <itemizedlist>

     <listitem>
      <para>
       Support compiling on <link
       linkend="install-windows">64-bit
       <productname>Windows</></link> and running in 64-bit
       mode (Tsutomu Yamada, Magnus Hagander)
      </para>

      <para>
       This allows for large shared memory sizes on <productname>Windows</>.
      </para>
     </listitem>

     <listitem>
      <para>
       Support server builds using <link
       linkend="install-windows-full"><productname>Visual Studio
       2008</></link> (Magnus Hagander)
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

  </sect3>

  <sect3>
   <title>Source Code</title>

   <itemizedlist>

    <listitem>
     <para>
      Distribute prebuilt documentation in a subdirectory tree, rather than
      as tar archive files inside the distribution tarball
      (Peter Eisentraut)
     </para>

     <para>
      For example, the prebuilt <acronym>HTML</> documentation is now in
      <filename>doc/src/sgml/html/</>; the manual pages are packaged
      similarly.
     </para>
    </listitem>

    <listitem>
     <para>
      Make the server's lexer reentrant (Tom Lane)
     </para>

     <para>
      This was needed for use of the lexer by PL/pgSQL.
     </para>
    </listitem>

    <listitem>
     <para>
      Improve speed of memory allocation (Tom Lane, Greg Stark)
     </para>
    </listitem>

    <listitem>
     <para>
      User-defined constraint triggers now have entries in
      <structname>pg_constraint</> as well as <structname>pg_trigger</>
      (Tom Lane)
     </para>

     <para>
      Because of this change,
      <structname>pg_constraint</>.<structfield>pgconstrname</> is now
      redundant and has been removed.
     </para>
    </listitem>

    <listitem>
     <para>
      Add system catalog columns
      <structname>pg_constraint</>.<structfield>conindid</> and
      <structname>pg_trigger</>.<structfield>tgconstrindid</>
      to better document the use of indexes for constraint
      enforcement (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Allow multiple conditions to be communicated to backends using a single
      operating system signal (Fujii Masao)
     </para>

     <para>
      This allows new features to be added without a platform-specific
      constraint on the number of signal conditions.
     </para>
    </listitem>

    <listitem>
     <para>
      Improve source code test coverage, including <filename>contrib</>, PL/Python,
      and PL/Perl (Peter Eisentraut, Andrew Dunstan)
     </para>
    </listitem>

    <listitem>
     <para>
      Remove the use of flat files for system table bootstrapping
      (Tom Lane, Alvaro Herrera)
     </para>

     <para>
      This improves performance when using many roles or
      databases, and eliminates some possible failure conditions.
     </para>
    </listitem>

    <listitem>
     <para>
      Automatically generate the initial contents of
      <structname>pg_attribute</> for <quote>bootstrapped</> catalogs
      (John Naylor)
     </para>

     <para>
      This greatly simplifies changes to these catalogs.
     </para>
    </listitem>

    <listitem>
     <para>
      Split the processing of
      <command>INSERT</>/<command>UPDATE</>/<command>DELETE</> operations out
      of <filename>execMain.c</> (Marko Tiikkaja)
     </para>

     <para>
      Updates are now executed in a separate ModifyTable node.  This change is
      necessary infrastructure for future improvements.
     </para>
    </listitem>

    <listitem>
     <para>
      Simplify translation of <application>psql</>'s SQL help text
      (Peter Eisentraut)
     </para>
    </listitem>

    <listitem>
     <para>
      Reduce the lengths of some file names so that all file paths in the
      distribution tarball are less than 100 characters (Tom Lane)
     </para>

     <para>
      Some decompression programs have problems with longer file paths.
     </para>
    </listitem>

    <listitem>
     <para>
      Add a new <link
      linkend="errcodes-table"><literal>ERRCODE_INVALID_PASSWORD</></link>
      <literal>SQLSTATE</> error code (Bruce Momjian)
     </para>
    </listitem>

    <listitem>
     <para>
      With authors' permissions, remove the few remaining personal source code
      copyright notices (Bruce Momjian)
     </para>

     <para>
      The personal copyright notices were insignificant but the community
      occasionally had to answer questions about them.
     </para>
    </listitem>

    <listitem>
     <para>
      Add new documentation <link linkend="non-durability">section</link>
      about running <productname>PostgreSQL</> in non-durable mode
      to improve performance (Bruce Momjian)
     </para>
    </listitem>

    <listitem>
     <para>
      Restructure the <acronym>HTML</> documentation
      <filename>Makefile</> rules to make their dependency checks work
      correctly, avoiding unnecessary rebuilds (Peter Eisentraut)
     </para>
    </listitem>

    <listitem>
     <para>
      Use <productname>DocBook</> <acronym>XSL</> stylesheets for man page
      building, rather than <productname>Docbook2X</> (Peter Eisentraut)
     </para>

     <para>
      This changes the set of tools needed to build the man pages.
     </para>
    </listitem>

    <listitem>
     <para>
      Improve PL/Perl code structure (Tim Bunce)
     </para>
    </listitem>

    <listitem>
     <para>
      Improve error context reports in PL/Perl (Alexey Klyukin)
     </para>
    </listitem>

   </itemizedlist>

   <sect4>
    <title>New Build Requirements</title>

     <para>
      Note that these requirements do not apply when building from a
      distribution tarball, since tarballs include the files that these
      programs are used to build.
     </para>

    <itemizedlist>
     <listitem>
      <para>
       Require <application>Autoconf</> 2.63 to build
       <application>configure</> (Peter Eisentraut)
      </para>
     </listitem>

     <listitem>
      <para>
       Require <application>Flex</> 2.5.31 or later to build
       from a <acronym>CVS</> checkout (Tom Lane)
      </para>
     </listitem>

     <listitem>
      <para>
       Require <application>Perl</> version 5.8 or later to build
       from a <acronym>CVS</> checkout (John Naylor, Andrew Dunstan)
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

   <sect4>
    <title>Portability</title>

    <itemizedlist>

     <listitem>
      <para>
       Use a more modern <acronym>API</> for <application>Bonjour</> (Tom Lane)
      </para>

      <para>
       Bonjour support now requires <productname>OS X</> 10.3 or later.
       The older API has been deprecated by Apple.
      </para>
     </listitem>

     <listitem>
      <para>
       Add spinlock support for the <productname>SuperH</>
       architecture (Nobuhiro Iwamatsu)
      </para>
     </listitem>

     <listitem>
      <para>
       Allow non-<application>GCC</> compilers to use inline functions if
       they support them (Kurt Harriman)
      </para>
     </listitem>

     <listitem>
      <para>
       Remove support for platforms that don't have a working 64-bit
       integer data type (Tom Lane)
      </para>
     </listitem>

     <listitem>
      <para>
       Restructure use of <literal>LDFLAGS</> to be more consistent
       across platforms (Tom Lane)
      </para>

      <para>
       <literal>LDFLAGS</> is now used for linking both executables and shared
       libraries, and we add on <literal>LDFLAGS_EX</> when linking
       executables, or <literal>LDFLAGS_SL</> when linking shared libraries.
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

   <sect4>
    <title>Server Programming</title>

    <itemizedlist>

     <listitem>
      <para>
       Make backend header files safe to include in <productname>C++</>
       (Kurt Harriman, Peter Eisentraut)
      </para>

      <para>
       These changes remove keyword conflicts that previously made
       <productname>C++</> usage difficult in backend code.  However, there
       are still other complexities when using <productname>C++</> for backend
       functions. <literal>extern "C" { }</> is still necessary in
       appropriate places, and memory management and error handling are
       still problematic.
      </para>
     </listitem>

     <listitem>
      <para>
       Add <link
       linkend="xaggr"><function>AggCheckCallContext()</></link>
       for use in detecting if a <productname>C</> function is
       being called as an aggregate (Hitoshi Harada)
      </para>
     </listitem>

     <listitem>
      <para>
       Change calling convention for <function>SearchSysCache()</> and related
       functions to avoid hard-wiring the maximum number of cache keys
       (Robert Haas)
      </para>

      <para>
       Existing calls will still work for the moment, but can be expected to
       break in 9.1 or later if not converted to the new style.
      </para>
     </listitem>

     <listitem>
      <para>
       Require calls of <function>fastgetattr()</> and
       <function>heap_getattr()</> backend macros to provide a non-NULL fourth
       argument (Robert Haas)
      </para>
     </listitem>

     <listitem>
      <para>
       Custom typanalyze functions should no longer rely on
       <structname>VacAttrStats</>.<structfield>attr</> to determine the type
       of data they will be passed (Tom Lane)
      </para>

      <para>
       This was changed to allow collection of statistics on index columns
       for which the storage type is different from the underlying column
       data type.  There are new fields that tell the actual datatype being
       analyzed.
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

   <sect4>
    <title>Server Hooks</title>

    <itemizedlist>

     <listitem>
      <para>
       Add parser hooks for processing ColumnRef and ParamRef nodes
       (Tom Lane)
      </para>
     </listitem>

     <listitem>
      <para>
       Add a ProcessUtility hook so loadable modules can control utility
       commands (Itagaki Takahiro)
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

   <sect4>
    <title>Binary Upgrade Support</title>

    <itemizedlist>

    <listitem>
     <para>
      Add <link linkend="pgupgrade"><filename>contrib/pg_upgrade</></link>
      to support in-place upgrades (Bruce Momjian)
     </para>

     <para>
      This avoids the requirement of dumping/reloading the database when
      upgrading to a new major release of PostgreSQL, thus reducing downtime
      by orders of magnitude. It supports upgrades to 9.0
      from PostgreSQL 8.3 and 8.4.
     </para>
    </listitem>

     <listitem>
      <para>
       Add support for preserving relation <link
       linkend="catalog-pg-class"><structname>relfilenode</></link> values
       during binary upgrades (Bruce Momjian)
      </para>
     </listitem>

     <listitem>
      <para>
       Add support for preserving <structname>pg_type</>
       and <structname>pg_enum</> OIDs during binary upgrades
       (Bruce Momjian)
      </para>
     </listitem>

     <listitem>
      <para>
       Move data files within tablespaces into
       <productname>PostgreSQL</>-version-specific subdirectories
       (Bruce Momjian)
      </para>

      <para>
       This simplifies binary upgrades.
      </para>
     </listitem>

    </itemizedlist>

   </sect4>

  </sect3>

  <sect3>
   <title>Contrib</title>

   <itemizedlist>

    <listitem>
     <para>
      Add multithreading option (<option>-j</>) to <link
      linkend="pgbench"><filename>contrib/pgbench</></link>
      (Itagaki Takahiro)
     </para>

     <para>
      This allows multiple <acronym>CPU</>s to be used by pgbench,
      reducing the risk of pgbench itself becoming the test bottleneck.
     </para>
    </listitem>

    <listitem>
     <para>
      Add <command>\shell</> and <command>\setshell</> meta
      commands to <link
      linkend="pgbench"><filename>contrib/pgbench</></link>
      (Michael Paquier)
     </para>
    </listitem>

    <listitem>
     <para>
      New features for <link
      linkend="dict-xsyn"><filename>contrib/dict_xsyn</></link>
      (Sergey Karpov)
     </para>

     <para>
      The new options are <literal>matchorig</>, <literal>matchsynonyms</>,
      and <literal>keepsynonyms</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Add full text dictionary <link
      linkend="unaccent"><filename>contrib/unaccent</></link>
      (Teodor Sigaev)
     </para>

     <para>
      This filtering dictionary removes accents from letters, which
      makes full-text searches over multiple languages much easier.
     </para>
    </listitem>

    <listitem>
     <para>
      Add <link
      linkend="CONTRIB-DBLINK-GET-NOTIFY"><function>dblink_get_notify()</></link>
      to <filename>contrib/dblink</> (Marcus Kempe)
     </para>

     <para>
      This allows asynchronous notifications in <productname>dblink</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Improve <filename>contrib/dblink</>'s handling of dropped columns
      (Tom Lane)
     </para>

     <para>
      This affects <link
      linkend="CONTRIB-DBLINK-BUILD-SQL-INSERT"><function>dblink_build_sql_insert()</></link>
      and related functions.  These functions now number columns according
      to logical not physical column numbers.
     </para>
    </listitem>

    <listitem>
     <para>
      Greatly increase <link
      linkend="hstore"><filename>contrib/hstore</></link>'s data
      length limit, and add B-tree and hash support so <literal>GROUP
      BY</> and <literal>DISTINCT</> operations are possible on
      <type>hstore</> columns (Andrew Gierth)
     </para>

     <para>
      New functions and operators were also added.  These improvements
      make <type>hstore</> a full-function key-value store embedded in
      <productname>PostgreSQL</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Add <link
      linkend="passwordcheck"><filename>contrib/passwordcheck</></link>
      to support site-specific password strength policies (Laurenz
      Albe)
     </para>

     <para>
      The source code of this module should be modified to implement
      site-specific password policies.
     </para>
    </listitem>

    <listitem>
     <para>
      Add <link
      linkend="pgarchivecleanup"><filename>contrib/pg_archivecleanup</></link>
      tool (Simon Riggs)
     </para>

     <para>
      This is designed to be used in the
      <literal>archive_cleanup_command</literal>
      server parameter, to remove no-longer-needed archive files.
     </para>
    </listitem>

    <listitem>
     <para>
      Add query text to <link
      linkend="auto-explain"><filename>contrib/auto_explain</></link>
      output (Andrew Dunstan)
     </para>
    </listitem>

    <listitem>
     <para>
      Add buffer access counters to <link
      linkend="pgstatstatements"><filename>contrib/pg_stat_statements</></link>
      (Itagaki Takahiro)
     </para>
    </listitem>

    <listitem>
     <para>
      Update <link
      linkend="server-start"><filename>contrib/start-scripts/linux</></link>
      to use <filename>/proc/self/oom_adj</> to disable the
      <link linkend="linux-memory-overcommit"><productname>Linux</>
      out-of-memory</link> (<acronym>OOM</>) killer (Alex
      Hunsaker, Tom Lane)
     </para>
    </listitem>

   </itemizedlist>

  </sect3>
 </sect2>
</sect1>
