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 <sect1 id="release-7-4-30">
  <title>Release 7.4.30</title>

  <note>
  <title>Release Date</title>
  <simpara>2010-10-04</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 7.4.29.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>

  <para>
   This is expected to be the last <productname>PostgreSQL</> release
   in the 7.4.X series.  Users are encouraged to update to a newer
   release branch soon.
  </para>

  <sect2>
   <title>Migration to Version 7.4.30</title>

   <para>
    A dump/restore is not required for those running 7.4.X.
    However, if you are upgrading from a version earlier than 7.4.26,
    see <xref linkend="release-7-4-26">.
   </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>
      Prevent possible crashes in <function>pg_get_expr()</> by disallowing
      it from being called with an argument that is not one of the system
      catalog columns it's intended to be used with
      (Heikki Linnakangas, Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <quote>cannot handle unplanned sub-select</quote> error (Tom Lane)
     </para>

     <para>
      This occurred when a sub-select contains a join alias reference that
      expands into an expression containing another sub-select.
     </para>
    </listitem>

    <listitem>
     <para>
      Take care to fsync the contents of lockfiles (both
      <filename>postmaster.pid</> and the socket lockfile) while writing them
      (Tom Lane)
     </para>

     <para>
      This omission could result in corrupted lockfile contents if the
      machine crashes shortly after postmaster start.  That could in turn
      prevent subsequent attempts to start the postmaster from succeeding,
      until the lockfile is manually removed.
     </para>
    </listitem>

    <listitem>
     <para>
      Improve <filename>contrib/dblink</>'s handling of tables containing
      dropped columns (Tom Lane)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix connection leak after <quote>duplicate connection name</quote>
      errors in <filename>contrib/dblink</> (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-7-4-29">
  <title>Release 7.4.29</title>

  <note>
  <title>Release Date</title>
  <simpara>2010-05-17</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 7.4.28.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>

  <para>
   The <productname>PostgreSQL</> community will stop releasing updates
   for the 7.4.X release series in July 2010.
   Users are encouraged to update to a newer release branch soon.
  </para>

  <sect2>
   <title>Migration to Version 7.4.29</title>

   <para>
    A dump/restore is not required for those running 7.4.X.
    However, if you are upgrading from a version earlier than 7.4.26,
    see <xref linkend="release-7-4-26">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Enforce restrictions in <literal>plperl</> using an opmask applied to
      the whole interpreter, instead of using <filename>Safe.pm</>
      (Tim Bunce, Andrew Dunstan)
     </para>

     <para>
      Recent developments have convinced us that <filename>Safe.pm</> is too
      insecure to rely on for making <literal>plperl</> trustable.  This
      change removes use of <filename>Safe.pm</> altogether, in favor of using
      a separate interpreter with an opcode mask that is always applied.
      Pleasant side effects of the change include that it is now possible to
      use Perl's <literal>strict</> pragma in a natural way in
      <literal>plperl</>, and that Perl's <literal>$a</> and <literal>$b</>
      variables work as expected in sort routines, and that function
      compilation is significantly faster.  (CVE-2010-1169)
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent PL/Tcl from executing untrustworthy code from
      <structname>pltcl_modules</> (Tom)
     </para>

     <para>
      PL/Tcl's feature for autoloading Tcl code from a database table
      could be exploited for trojan-horse attacks, because there was no
      restriction on who could create or insert into that table.  This change
      disables the feature unless <structname>pltcl_modules</> is owned by a
      superuser.  (However, the permissions on the table are not checked, so
      installations that really need a less-than-secure modules table can
      still grant suitable privileges to trusted non-superusers.)  Also,
      prevent loading code into the unrestricted <quote>normal</> Tcl
      interpreter unless we are really going to execute a <literal>pltclu</>
      function.  (CVE-2010-1170)
     </para>
    </listitem>

    <listitem>
     <para>
      Do not allow an unprivileged user to reset superuser-only parameter
      settings (Alvaro)
     </para>

     <para>
      Previously, if an unprivileged user ran <literal>ALTER USER ... RESET
      ALL</> for himself, or <literal>ALTER DATABASE ... RESET ALL</> for
      a database he owns, this would remove all special parameter settings
      for the user or database, even ones that are only supposed to be
      changeable by a superuser.  Now, the <command>ALTER</> will only
      remove the parameters that the user has permission to change.
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid possible crash during backend shutdown if shutdown occurs
      when a <literal>CONTEXT</> addition would be made to log entries (Tom)
     </para>

     <para>
      In some cases the context-printing function would fail because the
      current transaction had already been rolled back when it came time
      to print a log message.
     </para>
    </listitem>

    <listitem>
     <para>
      Update PL/Perl's <filename>ppport.h</> for modern Perl versions
      (Andrew)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix assorted memory leaks in PL/Python (Andreas Freund, Tom)
     </para>
    </listitem>

    <listitem>
     <para>
      Ensure that <filename>contrib/pgstattuple</> functions respond to cancel
      interrupts promptly (Tatsuhito Kasahara)
     </para>
    </listitem>

    <listitem>
     <para>
      Make server startup deal properly with the case that
      <function>shmget()</> returns <literal>EINVAL</> for an existing
      shared memory segment (Tom)
     </para>

     <para>
      This behavior has been observed on BSD-derived kernels including macOS.
      It resulted in an entirely-misleading startup failure complaining that
      the shared memory request size was too large.
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-28">
  <title>Release 7.4.28</title>

  <note>
  <title>Release Date</title>
  <simpara>2010-03-15</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 7.4.27.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>

  <para>
   The <productname>PostgreSQL</> community will stop releasing updates
   for the 7.4.X release series in July 2010.
   Users are encouraged to update to a newer release branch soon.
  </para>

  <sect2>
   <title>Migration to Version 7.4.28</title>

   <para>
    A dump/restore is not required for those running 7.4.X.
    However, if you are upgrading from a version earlier than 7.4.26,
    see <xref linkend="release-7-4-26">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Add new configuration parameter <varname>ssl_renegotiation_limit</> to
      control how often we do session key renegotiation for an SSL connection
      (Magnus)
     </para>

     <para>
      This can be set to zero to disable renegotiation completely, which may
      be required if a broken SSL library is used.  In particular, some
      vendors are shipping stopgap patches for CVE-2009-3555 that cause
      renegotiation attempts to fail.
     </para>
    </listitem>

    <listitem>
     <para>
      Make <function>substring()</> for <type>bit</> types treat any negative
      length as meaning <quote>all the rest of the string</> (Tom)
     </para>

     <para>
      The previous coding treated only -1 that way, and would produce an
      invalid result value for other negative values, possibly leading to
      a crash (CVE-2010-0442).
     </para>
    </listitem>

    <listitem>
     <para>
      Fix some cases of pathologically slow regular expression matching (Tom)
     </para>
    </listitem>

    <listitem>
     <para>
      When reading <filename>pg_hba.conf</> and related files, do not treat
      <literal>@something</> as a file inclusion request if the <literal>@</>
      appears inside quote marks; also, never treat <literal>@</> by itself
      as a file inclusion request (Tom)
     </para>

     <para>
      This prevents erratic behavior if a role or database name starts with
      <literal>@</>.  If you need to include a file whose path name
      contains spaces, you can still do so, but you must write
      <literal>@"/path to/file"</> rather than putting the quotes around
      the whole construct.
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent infinite loop on some platforms if a directory is named as
      an inclusion target in <filename>pg_hba.conf</> and related files
      (Tom)
     </para>
    </listitem>

    <listitem>
     <para>
      Ensure PL/Tcl initializes the Tcl interpreter fully (Tom)
     </para>

     <para>
      The only known symptom of this oversight is that the Tcl
      <literal>clock</> command misbehaves if using Tcl 8.5 or later.
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent crash in <filename>contrib/dblink</> when too many key
      columns are specified to a <function>dblink_build_sql_*</> function
      (Rushabh Lathia, Joe Conway)
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-27">
  <title>Release 7.4.27</title>

  <note>
  <title>Release Date</title>
  <simpara>2009-12-14</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 7.4.26.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>

  <sect2>
   <title>Migration to Version 7.4.27</title>

   <para>
    A dump/restore is not required for those running 7.4.X.
    However, if you are upgrading from a version earlier than 7.4.26,
    see <xref linkend="release-7-4-26">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Protect against indirect security threats caused by index functions
      changing session-local state (Gurjeet Singh, Tom)
     </para>

     <para>
      This change prevents allegedly-immutable index functions from possibly
      subverting a superuser's session (CVE-2009-4136).
     </para>
    </listitem>

    <listitem>
     <para>
      Reject SSL certificates containing an embedded null byte in the common
      name (CN) field (Magnus)
     </para>

     <para>
      This prevents unintended matching of a certificate to a server or client
      name during SSL validation (CVE-2009-4034).
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possible crash during backend-startup-time cache initialization (Tom)
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent signals from interrupting <literal>VACUUM</> at unsafe times
      (Alvaro)
     </para>

     <para>
      This fix prevents a PANIC if a <literal>VACUUM FULL</> is canceled
      after it's already committed its tuple movements, as well as transient
      errors if a plain <literal>VACUUM</> is interrupted after having
      truncated the table.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix possible crash due to integer overflow in hash table size
      calculation (Tom)
     </para>

     <para>
      This could occur with extremely large planner estimates for the size of
      a hashjoin's result.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix very rare crash in <type>inet</>/<type>cidr</> comparisons (Chris
      Mikkelson)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix PAM password processing to be more robust (Tom)
     </para>

     <para>
      The previous code is known to fail with the combination of the Linux
      <literal>pam_krb5</> PAM module with Microsoft Active Directory as the
      domain controller.  It might have problems elsewhere too, since it was
      making unjustified assumptions about what arguments the PAM stack would
      pass to it.
     </para>
    </listitem>

    <listitem>
     <para>
      Make the postmaster ignore any <literal>application_name</> parameter in
      connection request packets, to improve compatibility with future libpq
      versions (Tom)
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-26">
  <title>Release 7.4.26</title>

  <note>
  <title>Release Date</title>
  <simpara>2009-09-09</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 7.4.25.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>

  <sect2>
   <title>Migration to Version 7.4.26</title>

   <para>
    A dump/restore is not required for those running 7.4.X.
    However, if you have any hash indexes on <type>interval</> columns,
    you must <command>REINDEX</> them after updating to 7.4.26.
    Also, if you are upgrading from a version earlier than 7.4.11,
    see <xref linkend="release-7-4-11">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Disallow <command>RESET ROLE</> and <command>RESET SESSION
      AUTHORIZATION</> inside security-definer functions (Tom, Heikki)
     </para>

     <para>
      This covers a case that was missed in the previous patch that
      disallowed <command>SET ROLE</> and <command>SET SESSION
      AUTHORIZATION</> inside security-definer functions.
      (See CVE-2007-6600)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix handling of sub-SELECTs appearing in the arguments of
      an outer-level aggregate function (Tom)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix hash calculation for data type <type>interval</> (Tom)
     </para>

     <para>
      This corrects wrong results for hash joins on interval values.
      It also changes the contents of hash indexes on interval columns.
      If you have any such indexes, you must <command>REINDEX</> them
      after updating.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix overflow for <literal>INTERVAL '<replaceable>x</> ms'</literal>
      when <replaceable>x</> is more than 2 million and integer
      datetimes are in use (Alex Hunsaker)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix calculation of distance between a point and a line segment (Tom)
     </para>

     <para>
      This led to incorrect results from a number of geometric operators.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <type>money</> data type to work in locales where currency
      amounts have no fractional digits, e.g. Japan (Itagaki Takahiro)
     </para>
    </listitem>

    <listitem>
     <para>
      Properly round datetime input like
      <literal>00:12:57.9999999999999999999999999999</> (Tom)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix poor choice of page split point in GiST R-tree operator classes
      (Teodor)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix portability issues in plperl initialization (Andrew Dunstan)
     </para>
    </listitem>

    <listitem>
     <para>
      Improve robustness of <application>libpq</>'s code to recover
      from errors during <command>COPY FROM STDIN</> (Tom)
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid including conflicting readline and editline header files
      when both libraries are installed (Zdenek Kotala)
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-25">
  <title>Release 7.4.25</title>

  <note>
  <title>Release Date</title>
  <simpara>2009-03-16</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 7.4.24.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>

  <sect2>
   <title>Migration to Version 7.4.25</title>

   <para>
    A dump/restore is not required for those running 7.4.X.
    However, if you are upgrading from a version earlier than 7.4.11,
    see <xref linkend="release-7-4-11">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Prevent error recursion crashes when encoding conversion fails (Tom)
     </para>

     <para>
      This change extends fixes made in the last two minor releases for
      related failure scenarios.  The previous fixes were narrowly tailored
      for the original problem reports, but we have now recognized that
      <emphasis>any</> error thrown by an encoding conversion function could
      potentially lead to infinite recursion while trying to report the
      error.  The solution therefore is to disable translation and encoding
      conversion and report the plain-ASCII form of any error message,
      if we find we have gotten into a recursive error reporting situation.
      (CVE-2009-0922)
     </para>
    </listitem>

    <listitem>
     <para>
      Disallow <command>CREATE CONVERSION</> with the wrong encodings
      for the specified conversion function (Heikki)
     </para>

     <para>
      This prevents one possible scenario for encoding conversion failure.
      The previous change is a backstop to guard against other kinds of
      failures in the same area.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix core dump when <function>to_char()</> is given format codes that
      are inappropriate for the type of the data argument (Tom)
     </para>
    </listitem>

    <listitem>
     <para>
      Add <literal>MUST</> (Mauritius Island Summer Time) to the default list
      of known timezone abbreviations (Xavier Bugaud)
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-24">
  <title>Release 7.4.24</title>

  <note>
  <title>Release Date</title>
  <simpara>2009-02-02</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 7.4.23.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>

  <sect2>
   <title>Migration to Version 7.4.24</title>

   <para>
    A dump/restore is not required for those running 7.4.X.
    However, if you are upgrading from a version earlier than 7.4.11,
    see <xref linkend="release-7-4-11">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Improve handling of URLs in <function>headline()</> function (Teodor)
     </para>
    </listitem>

    <listitem>
     <para>
      Improve handling of overlength headlines in <function>headline()</>
      function (Teodor)
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent possible Assert failure or misconversion if an encoding
      conversion is created with the wrong conversion function for the
      specified pair of encodings (Tom, Heikki)
     </para>
    </listitem>

    <listitem>
     <para>
      Avoid unnecessary locking of small tables in <command>VACUUM</>
      (Heikki)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix uninitialized variables in <filename>contrib/tsearch2</>'s
      <function>get_covers()</> function (Teodor)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix bug in <function>to_char()</>'s handling of <literal>TH</>
      format codes (Andreas Scherbaum)
     </para>
    </listitem>

    <listitem>
     <para>
      Make all documentation reference <literal>pgsql-bugs</> and/or
      <literal>pgsql-hackers</> as appropriate, instead of the
      now-decommissioned <literal>pgsql-ports</> and <literal>pgsql-patches</>
      mailing lists (Tom)
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-23">
  <title>Release 7.4.23</title>

  <note>
  <title>Release Date</title>
  <simpara>2008-11-03</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 7.4.22.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>

  <sect2>
   <title>Migration to Version 7.4.23</title>

   <para>
    A dump/restore is not required for those running 7.4.X.
    However, if you are upgrading from a version earlier than 7.4.11,
    see <xref linkend="release-7-4-11">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Fix backend crash when the client encoding cannot represent a localized
      error message (Tom)
     </para>

     <para>
      We have addressed similar issues before, but it would still fail if
      the <quote>character has no equivalent</> message itself couldn't
      be converted.  The fix is to disable localization and send the plain
      ASCII error message when we detect such a situation.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix incorrect tsearch2 headline generation when single query
      item matches first word of text (Sushant Sinha)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix improper display of fractional seconds in interval values when
      using a non-ISO datestyle in an <option>--enable-integer-datetimes</>
      build (Ron Mayer)
     </para>
    </listitem>

    <listitem>
     <para>
      Ensure <function>SPI_getvalue</> and <function>SPI_getbinval</>
      behave correctly when the passed tuple and tuple descriptor have
      different numbers of columns (Tom)
     </para>

     <para>
      This situation is normal when a table has had columns added or removed,
      but these two functions didn't handle it properly.
      The only likely consequence is an incorrect error indication.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>ecpg</>'s parsing of <command>CREATE USER</> (Michael)
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-22">
  <title>Release 7.4.22</title>

  <note>
  <title>Release Date</title>
  <simpara>2008-09-22</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 7.4.21.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>

  <sect2>
   <title>Migration to Version 7.4.22</title>

   <para>
    A dump/restore is not required for those running 7.4.X.
    However, if you are upgrading from a version earlier than 7.4.11,
    see <xref linkend="release-7-4-11">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Fix datetime input functions to correctly detect integer overflow when
      running on a 64-bit platform (Tom)
     </para>
    </listitem>

    <listitem>
     <para>
      Improve performance of writing very long log messages to syslog (Tom)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix bug in backwards scanning of a cursor on a <literal>SELECT DISTINCT
      ON</> query (Tom)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix planner to estimate that <literal>GROUP BY</> expressions yielding
      boolean results always result in two groups, regardless of the
      expressions' contents (Tom)
     </para>

     <para>
      This is very substantially more accurate than the regular <literal>GROUP
      BY</> estimate for certain boolean tests like <replaceable>col</>
      <literal>IS NULL</>.
     </para>
    </listitem>

    <listitem>
     <para>
      Improve <application>pg_dump</> and <application>pg_restore</>'s
      error reporting after failure to send a SQL command (Tom)
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-21">
  <title>Release 7.4.21</title>

  <note>
  <title>Release Date</title>
  <simpara>2008-06-12</simpara>
  </note>

  <para>
   This release contains one serious bug fix over 7.4.20.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>

  <sect2>
   <title>Migration to Version 7.4.21</title>

   <para>
    A dump/restore is not required for those running 7.4.X.
    However, if you are upgrading from a version earlier than 7.4.11,
    see <xref linkend="release-7-4-11">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Make <function>pg_get_ruledef()</> parenthesize negative constants (Tom)
     </para>

     <para>
      Before this fix, a negative constant in a view or rule might be dumped
      as, say, <literal>-42::integer</>, which is subtly incorrect: it should
      be <literal>(-42)::integer</> due to operator precedence rules.
      Usually this would make little difference, but it could interact with
      another recent patch to cause
      <productname>PostgreSQL</> to reject what had been a valid
      <command>SELECT DISTINCT</> view query.  Since this could result in
      <application>pg_dump</> output failing to reload, it is being treated
      as a high-priority fix.  The only released versions in which dump
      output is actually incorrect are 8.3.1 and 8.2.7.
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-20">
  <title>Release 7.4.20</title>

  <note>
  <title>Release Date</title>
  <simpara>never released</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 7.4.19.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>

  <sect2>
   <title>Migration to Version 7.4.20</title>

   <para>
    A dump/restore is not required for those running 7.4.X.
    However, if you are upgrading from a version earlier than 7.4.11,
    see <xref linkend="release-7-4-11">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Fix conversions between ISO-8859-5 and other encodings to handle
      Cyrillic <quote>Yo</> characters (<literal>e</> and <literal>E</> with
      two dots) (Sergey Burladyan)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix a few datatype input functions
      that were allowing unused bytes in their results to contain
      uninitialized, unpredictable values (Tom)
     </para>

     <para>
      This could lead to failures in which two apparently identical literal
      values were not seen as equal, resulting in the parser complaining
      about unmatched <literal>ORDER BY</> and <literal>DISTINCT</>
      expressions.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix a corner case in regular-expression substring matching
      (<literal>substring(<replaceable>string</> from
      <replaceable>pattern</>)</literal>) (Tom)
     </para>

     <para>
      The problem occurs when there is a match to the pattern overall but
      the user has specified a parenthesized subexpression and that
      subexpression hasn't got a match.  An example is
      <literal>substring('foo' from 'foo(bar)?')</>.
      This should return NULL, since <literal>(bar)</> isn't matched, but
      it was mistakenly returning the whole-pattern match instead (ie,
      <literal>foo</>).
     </para>
    </listitem>

    <listitem>
     <para>
      Fix incorrect result from <application>ecpg</>'s
      <function>PGTYPEStimestamp_sub()</> function (Michael)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <literal>DatumGetBool</> macro to not fail with <application>gcc</>
      4.3 (Tom)
     </para>

     <para>
      This problem affects <quote>old style</> (V0) C functions that
      return boolean.  The fix is already in 8.3, but the need to
      back-patch it was not realized at the time.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix longstanding <command>LISTEN</>/<command>NOTIFY</>
      race condition (Tom)
     </para>

     <para>
      In rare cases a session that had just executed a
      <command>LISTEN</> might not get a notification, even though
      one would be expected because the concurrent transaction executing
      <command>NOTIFY</> was observed to commit later.
     </para>

     <para>
      A side effect of the fix is that a transaction that has executed
      a not-yet-committed <command>LISTEN</> command will not see any
      row in <structname>pg_listener</> for the <command>LISTEN</>,
      should it choose to look; formerly it would have.  This behavior
      was never documented one way or the other, but it is possible that
      some applications depend on the old behavior.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix display of constant expressions in <literal>ORDER BY</>
      and <literal>GROUP BY</> (Tom)
     </para>

     <para>
      An explicitly casted constant would be shown incorrectly.  This could
      for example lead to corruption of a view definition during
      dump and reload.
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <application>libpq</> to handle NOTICE messages correctly
      during COPY OUT (Tom)
     </para>

     <para>
      This failure has only been observed to occur when a user-defined
      datatype's output routine issues a NOTICE, but there is no
      guarantee it couldn't happen due to other causes.
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-19">
  <title>Release 7.4.19</title>

  <note>
  <title>Release Date</title>
  <simpara>2008-01-07</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 7.4.18,
   including fixes for significant security issues.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>

  <sect2>
   <title>Migration to Version 7.4.19</title>

   <para>
    A dump/restore is not required for those running 7.4.X.  However,
    if you are upgrading from a version earlier than 7.4.11,
    see <xref linkend="release-7-4-11">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Prevent functions in indexes from executing with the privileges of
      the user running <command>VACUUM</>, <command>ANALYZE</>, etc (Tom)
     </para>

     <para>
      Functions used in index expressions and partial-index
      predicates are evaluated whenever a new table entry is made.  It has
      long been understood that this poses a risk of trojan-horse code
      execution if one modifies a table owned by an untrustworthy user.
      (Note that triggers, defaults, check constraints, etc. pose the
      same type of risk.)  But functions in indexes pose extra danger
      because they will be executed by routine maintenance operations
      such as <command>VACUUM FULL</>, which are commonly performed
      automatically under a superuser account.  For example, a nefarious user
      can execute code with superuser privileges by setting up a
      trojan-horse index definition and waiting for the next routine vacuum.
      The fix arranges for standard maintenance operations
      (including <command>VACUUM</>, <command>ANALYZE</>, <command>REINDEX</>,
      and <command>CLUSTER</>) to execute as the table owner rather than
      the calling user, using the same privilege-switching mechanism already
      used for <literal>SECURITY DEFINER</> functions.  To prevent bypassing
      this security measure, execution of <command>SET SESSION
      AUTHORIZATION</> and <command>SET ROLE</> is now forbidden within a
      <literal>SECURITY DEFINER</> context.  (CVE-2007-6600)
     </para>
    </listitem>

    <listitem>
     <para>
      Repair assorted bugs in the regular-expression package (Tom, Will Drewry)
     </para>

     <para>
      Suitably crafted regular-expression patterns could cause crashes,
      infinite or near-infinite looping, and/or massive memory consumption,
      all of which pose denial-of-service hazards for applications that
      accept regex search patterns from untrustworthy sources.
      (CVE-2007-4769, CVE-2007-4772, CVE-2007-6067)
     </para>
    </listitem>

    <listitem>
     <para>
      Require non-superusers who use <filename>/contrib/dblink</> to use only
      password authentication, as a security measure (Joe)
     </para>

     <para>
      The fix that appeared for this in 7.4.18 was incomplete, as it plugged
      the hole for only some <filename>dblink</> functions.  (CVE-2007-6601,
      CVE-2007-3278)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix planner failure in some cases of <literal>WHERE false AND var IN
      (SELECT ...)</> (Tom)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix potential crash in <function>translate()</> when using a multibyte
      database encoding (Tom)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix PL/Python to not crash on long exception messages (Alvaro)
     </para>
    </listitem>

    <listitem>
     <para>
      <application>ecpg</> parser fixes (Michael)
     </para>
    </listitem>

    <listitem>
     <para>
      Make <filename>contrib/tablefunc</>'s <function>crosstab()</> handle
      NULL rowid as a category in its own right, rather than crashing (Joe)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix <type>tsvector</> and <type>tsquery</> output routines to
      escape backslashes correctly (Teodor, Bruce)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix crash of <function>to_tsvector()</> on huge input strings (Teodor)
     </para>
    </listitem>

    <listitem>
     <para>
      Require a specific version of <productname>Autoconf</> to be used
      when re-generating the <command>configure</> script (Peter)
     </para>

     <para>
      This affects developers and packagers only.  The change was made
      to prevent accidental use of untested combinations of
      <productname>Autoconf</> and <productname>PostgreSQL</> versions.
      You can remove the version check if you really want to use a
      different <productname>Autoconf</> version, but it's
      your responsibility whether the result works or not.
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-18">
  <title>Release 7.4.18</title>

  <note>
  <title>Release Date</title>
  <simpara>2007-09-17</simpara>
  </note>

  <para>
   This release contains fixes from 7.4.17.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>

  <sect2>
   <title>Migration to Version 7.4.18</title>

   <para>
    A dump/restore is not required for those running 7.4.X.  However,
    if you are upgrading from a version earlier than 7.4.11,
    see <xref linkend="release-7-4-11">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Prevent index corruption when a transaction inserts rows and
      then aborts close to the end of a concurrent <command>VACUUM</>
      on the same table (Tom)
     </para>
    </listitem>

    <listitem>
     <para>
      Make <command>CREATE DOMAIN ... DEFAULT NULL</> work properly (Tom)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix excessive logging of <acronym>SSL</> error messages (Tom)
     </para>
    </listitem>

    <listitem>
     <para>
      Fix crash when <varname>log_min_error_statement</> logging runs out
      of memory (Tom)
     </para>
    </listitem>

    <listitem>
     <para>
      Prevent <command>CLUSTER</> from failing
      due to attempting to process temporary tables of other sessions (Alvaro)
     </para>
    </listitem>

    <listitem>
     <para>
      Require non-superusers who use <filename>/contrib/dblink</> to use only
      password authentication, as a security measure (Joe)
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-17">
  <title>Release 7.4.17</title>

  <note>
  <title>Release Date</title>
  <simpara>2007-04-23</simpara>
  </note>

  <para>
   This release contains fixes from 7.4.16,
   including a security fix.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>

  <sect2>
   <title>Migration to Version 7.4.17</title>

   <para>
    A dump/restore is not required for those running 7.4.X.  However,
    if you are upgrading from a version earlier than 7.4.11,
    see <xref linkend="release-7-4-11">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
    <para>
     Support explicit placement of the temporary-table schema within
     <varname>search_path</>, and disable searching it for functions
     and operators (Tom)
    </para>
    <para>
     This is needed to allow a security-definer function to set a
     truly secure value of <varname>search_path</>.  Without it,
     an unprivileged SQL user can use temporary objects to execute code
     with the privileges of the security-definer function (CVE-2007-2138).
     See <command>CREATE FUNCTION</> for more information.
    </para>
    </listitem>

    <listitem>
    <para>
     <filename>/contrib/tsearch2</> crash fixes (Teodor)
    </para>
    </listitem>

    <listitem>
    <para>
     Fix potential-data-corruption bug in how <command>VACUUM FULL</> handles
     <command>UPDATE</> chains (Tom, Pavan Deolasee)
    </para>
    </listitem>

    <listitem>
    <para>
     Fix PANIC during enlargement of a hash index (bug introduced in 7.4.15)
     (Tom)
    </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-16">
  <title>Release 7.4.16</title>

  <note>
  <title>Release Date</title>
  <simpara>2007-02-05</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 7.4.15, including
   a security fix.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>

  <sect2>
   <title>Migration to Version 7.4.16</title>

   <para>
    A dump/restore is not required for those running 7.4.X.  However,
    if you are upgrading from a version earlier than 7.4.11,
    see <xref linkend="release-7-4-11">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
    <para>
     Remove security vulnerability that allowed connected users
     to read backend memory (Tom)
    </para>
    <para>
     The vulnerability involves suppressing the normal check that a SQL
     function returns the data type it's declared to, or changing the
     data type of a table column used in a SQL function (CVE-2007-0555).
     This error can easily be exploited to cause a backend crash, and in
     principle might be used to read database content that the user
     should not be able to access.
    </para>
    </listitem>

    <listitem>
    <para>
     Fix rare bug wherein btree index page splits could fail
     due to choosing an infeasible split point (Heikki Linnakangas)
    </para>
    </listitem>

    <listitem>
    <para>
     Fix for rare Assert() crash triggered by <literal>UNION</> (Tom)
    </para>
    </listitem>

    <listitem>
    <para>
     Tighten security of multi-byte character processing for UTF8 sequences
     over three bytes long (Tom)
    </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-15">
  <title>Release 7.4.15</title>

  <note>
  <title>Release Date</title>
  <simpara>2007-01-08</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 7.4.14.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>

  <sect2>
   <title>Migration to Version 7.4.15</title>

   <para>
    A dump/restore is not required for those running 7.4.X.  However,
    if you are upgrading from a version earlier than 7.4.11,
    see <xref linkend="release-7-4-11">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

   <itemizedlist>

    <listitem>
     <para>
      Improve handling of <function>getaddrinfo()</> on AIX (Tom)
     </para>

     <para>
      This fixes a problem with starting the statistics collector,
      among other things.
     </para>
    </listitem>

     <listitem>
      <para>
       Fix <quote>failed to re-find parent key</> errors in
       <command>VACUUM</> (Tom)
      </para>
     </listitem>

     <listitem>
      <para>
       Fix bugs affecting multi-gigabyte hash indexes (Tom)
      </para>
     </listitem>

    <listitem>
     <para>
      Fix error when constructing an <literal>ARRAY[]</> made up of multiple
      empty elements (Tom)
     </para>
    </listitem>

    <listitem>
     <para>
      <function>to_number()</> and <function>to_char(numeric)</>
      are now <literal>STABLE</>, not <literal>IMMUTABLE</>, for
      new <application>initdb</> installs (Tom)
     </para>

     <para>
      This is because <varname>lc_numeric</> can potentially
      change the output of these functions.
     </para>
    </listitem>

    <listitem>
     <para>
      Improve index usage of regular expressions that use parentheses (Tom)
     </para>

     <para>
      This improves <application>psql</> <literal>\d</> performance also.
     </para>
    </listitem>

   </itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-14">
  <title>Release 7.4.14</title>

  <note>
  <title>Release Date</title>
  <simpara>2006-10-16</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 7.4.13.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>

  <sect2>
   <title>Migration to Version 7.4.14</title>

   <para>
    A dump/restore is not required for those running 7.4.X.  However,
    if you are upgrading from a version earlier than 7.4.11,
    see <xref linkend="release-7-4-11">.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

<itemizedlist>
<listitem><para>Fix core dump when an untyped literal is taken as
ANYARRAY</para></listitem>
<listitem><para>Fix <function>string_to_array()</> to handle overlapping
 matches for the separator string</para>
<para>For example, <literal>string_to_array('123xx456xxx789', 'xx')</>.
</para></listitem>
<listitem><para>Fix corner cases in pattern matching for
 <application>psql</>'s <literal>\d</> commands</para></listitem>
<listitem><para>Fix index-corrupting bugs in /contrib/ltree
 (Teodor)</para></listitem>
<listitem><para>Fix backslash escaping in /contrib/dbmirror</para></listitem>
<listitem><para>Adjust regression tests for recent changes in US DST laws
</para> </listitem>
</itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-13">
  <title>Release 7.4.13</title>

  <note>
  <title>Release Date</title>
  <simpara>2006-05-23</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 7.4.12,
   including patches for extremely serious security issues.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>

  <sect2>
   <title>Migration to Version 7.4.13</title>

   <para>
    A dump/restore is not required for those running 7.4.X.  However,
    if you are upgrading from a version earlier than 7.4.11,
    see <xref linkend="release-7-4-11">.
   </para>

   <para>
    Full security against the SQL-injection attacks described in
    CVE-2006-2313 and CVE-2006-2314 might require changes in application
    code.  If you have applications that embed untrustworthy strings
    into SQL commands, you should examine them as soon as possible to
    ensure that they are using recommended escaping techniques.  In
    most cases, applications should be using subroutines provided by
    libraries or drivers (such as <application>libpq</>'s
    <function>PQescapeStringConn()</>) to perform string escaping,
    rather than relying on <foreignphrase>ad hoc</> code to do it.
   </para>
  </sect2>

  <sect2>
   <title>Changes</title>

<itemizedlist>
<listitem><para>Change the server to reject invalidly-encoded multibyte
characters in all cases (Tatsuo, Tom)</para>
<para>While <productname>PostgreSQL</> has been moving in this direction for
some time, the checks are now applied uniformly to all encodings and all
textual input, and are now always errors not merely warnings.  This change
defends against SQL-injection attacks of the type described in CVE-2006-2313.
</para></listitem>

<listitem><para>Reject unsafe uses of <literal>\'</> in string literals</para>
<para>As a server-side defense against SQL-injection attacks of the type
described in CVE-2006-2314, the server now only accepts <literal>''</> and not
<literal>\'</> as a representation of ASCII single quote in SQL string
literals.  By default, <literal>\'</> is rejected only when
<varname>client_encoding</> is set to a client-only encoding (SJIS, BIG5, GBK,
GB18030, or UHC), which is the scenario in which SQL injection is possible.
A new configuration parameter <varname>backslash_quote</> is available to
adjust this behavior when needed.  Note that full security against
CVE-2006-2314 might require client-side changes; the purpose of
<varname>backslash_quote</> is in part to make it obvious that insecure
clients are insecure.
</para></listitem>

<listitem><para>Modify <application>libpq</>'s string-escaping routines to be
aware of encoding considerations and
<varname>standard_conforming_strings</></para>
<para>This fixes <application>libpq</>-using applications for the security
issues described in CVE-2006-2313 and CVE-2006-2314, and also future-proofs
them against the planned changeover to SQL-standard string literal syntax.
Applications that use multiple <productname>PostgreSQL</> connections
concurrently should migrate to <function>PQescapeStringConn()</> and
<function>PQescapeByteaConn()</> to ensure that escaping is done correctly
for the settings in use in each database connection.  Applications that
do string escaping <quote>by hand</> should be modified to rely on library
routines instead.
</para></listitem>

<listitem><para>Fix some incorrect encoding conversion functions</para>
<para><function>win1251_to_iso</>, <function>alt_to_iso</>,
<function>euc_tw_to_big5</>, <function>euc_tw_to_mic</>,
<function>mic_to_euc_tw</> were all broken to varying
extents.
</para></listitem>

<listitem><para>Clean up stray remaining uses of <literal>\'</> in strings
(Bruce, Jan)</para></listitem>

<listitem><para>Fix bug that sometimes caused OR'd index scans to
miss rows they should have returned</para></listitem>

<listitem><para>Fix WAL replay for case where a btree index has been
truncated</para></listitem>

<listitem><para>Fix <literal>SIMILAR TO</> for patterns involving
<literal>|</> (Tom)</para></listitem>

<listitem><para>Fix server to use custom DH SSL parameters correctly (Michael
Fuhr)</para></listitem>

<listitem><para>Fix for Bonjour on Intel Macs (Ashley Clark)</para></listitem>

<listitem><para>Fix various minor memory leaks</para></listitem>
</itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-12">
  <title>Release 7.4.12</title>

  <note>
  <title>Release Date</title>
  <simpara>2006-02-14</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 7.4.11.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>

  <sect2>
   <title>Migration to Version 7.4.12</title>

   <para>
    A dump/restore is not required for those running 7.4.X.  However,
    if you are upgrading from a version earlier than 7.4.11,
    see <xref linkend="release-7-4-11">.
   </para>
  </sect2>

  <sect2>
   <title>Changes</title>

<itemizedlist>

<listitem><para>Fix potential crash in <command>SET
SESSION AUTHORIZATION</> (CVE-2006-0553)</para>
<para>An unprivileged user could crash the server process, resulting in
momentary denial of service to other users, if the server has been compiled
with Asserts enabled (which is not the default).
Thanks to Akio Ishida for reporting this problem.
</para></listitem>

<listitem><para>Fix bug with row visibility logic in self-inserted
rows (Tom)</para>
<para>Under rare circumstances a row inserted by the current command
could be seen as already valid, when it should not be.  Repairs bug
created in 7.4.9 and 7.3.11 releases.
</para></listitem>

<listitem><para>Fix race condition that could lead to <quote>file already
exists</> errors during pg_clog file creation
(Tom)</para></listitem>

<listitem><para>Properly check <literal>DOMAIN</> constraints for
<literal>UNKNOWN</> parameters in prepared statements
(Neil)</para></listitem>

<listitem><para>Fix to allow restoring dumps that have cross-schema
references to custom operators (Tom)</para></listitem>

<listitem><para>Portability fix for testing presence of <function>finite</>
and <function>isinf</> during configure (Tom)</para></listitem>

</itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-11">
  <title>Release 7.4.11</title>

  <note>
  <title>Release Date</title>
  <simpara>2006-01-09</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 7.4.10.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>

  <sect2>
   <title>Migration to Version 7.4.11</title>

   <para>
    A dump/restore is not required for those running 7.4.X.  However,
    if you are upgrading from a version earlier than 7.4.8,
    see <xref linkend="release-7-4-8">.
    Also, you might need to <command>REINDEX</> indexes on textual
    columns after updating, if you are affected by the locale or
    <application>plperl</> issues described below.
   </para>
  </sect2>

  <sect2>
   <title>Changes</title>

<itemizedlist>

<listitem><para>Fix for protocol-level Describe messages issued
outside a transaction or in a failed transaction (Tom)</para></listitem>

<listitem><para>Fix character string comparison for locales that consider
different character combinations as equal, such as Hungarian (Tom)</para>
<para>This might require <command>REINDEX</> to fix existing indexes on
textual columns.</para></listitem>

<listitem><para>Set locale environment variables during postmaster startup
to ensure that <application>plperl</> won't change the locale later</para>
<para>This fixes a problem that occurred if the <application>postmaster</> was
started with environment variables specifying a different locale than what
<application>initdb</> had been told.  Under these conditions, any use of
<application>plperl</> was likely to lead to corrupt indexes.  You might need
<command>REINDEX</> to fix existing indexes on
textual columns if this has happened to you.</para></listitem>

<listitem><para>Fix longstanding bug in strpos() and regular expression
handling in certain rarely used Asian multi-byte character sets (Tatsuo)
</para></listitem>

<listitem><para>Fix bug in <filename>/contrib/pgcrypto</> gen_salt,
which caused it not to use all available salt space for MD5 and
XDES algorithms (Marko Kreen, Solar Designer)</para>
<para>Salts for Blowfish and standard DES are unaffected.</para></listitem>

<listitem><para>Fix <filename>/contrib/dblink</> to throw an error,
rather than crashing, when the number of columns specified is different from
what's actually returned by the query (Joe)</para></listitem>

</itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-10">
  <title>Release 7.4.10</title>

  <note>
  <title>Release Date</title>
  <simpara>2005-12-12</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 7.4.9.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>

  <sect2>
   <title>Migration to Version 7.4.10</title>

   <para>
    A dump/restore is not required for those running 7.4.X.  However,
    if you are upgrading from a version earlier than 7.4.8,
    see <xref linkend="release-7-4-8">.
   </para>
  </sect2>

  <sect2>
   <title>Changes</title>

<itemizedlist>

<listitem><para>Fix race condition in transaction log management</para>
<para>There was a narrow window in which an I/O operation could be initiated
for the wrong page, leading to an Assert failure or data
corruption.</para>
</listitem>

<listitem><para>Prevent failure if client sends Bind protocol message
when current transaction is already aborted</para></listitem>

<listitem><para><filename>/contrib/ltree</> fixes (Teodor)</para></listitem>

<listitem><para>AIX and HPUX compile fixes (Tom)</para></listitem>

<listitem><para>Fix longstanding planning error for outer joins</para>
<para>This bug sometimes caused a bogus error <quote>RIGHT JOIN is
only supported with merge-joinable join conditions</>.</para></listitem>

<listitem><para>Prevent core dump in <application>pg_autovacuum</> when a
table has been dropped</para></listitem>
</itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-9">
  <title>Release 7.4.9</title>

  <note>
  <title>Release Date</title>
  <simpara>2005-10-04</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 7.4.8.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>

  <sect2>
   <title>Migration to Version 7.4.9</title>

   <para>
    A dump/restore is not required for those running 7.4.X.  However,
    if you are upgrading from a version earlier than 7.4.8,
    see <xref linkend="release-7-4-8">.
   </para>
  </sect2>

  <sect2>
   <title>Changes</title>

<itemizedlist>
<listitem><para>Fix error that allowed <command>VACUUM</> to remove
<literal>ctid</> chains too soon, and add more checking in code that follows
<literal>ctid</> links</para>
<para>This fixes a long-standing problem that could cause crashes in very rare
circumstances.</para></listitem>
<listitem><para>Fix <type>CHAR()</> to properly pad spaces to the specified
length when using a multiple-byte character set (Yoshiyuki Asaba)</para>
<para>In prior releases, the padding of <type>CHAR()</> was incorrect
because it only padded to the specified number of bytes without
considering how many characters were stored.</para></listitem>
<listitem><para>Fix the sense of the test for read-only transaction
in <command>COPY</></para>
<para>The code formerly prohibited <command>COPY TO</>, where it should
prohibit <command>COPY FROM</>.
</para></listitem>
<listitem><para>Fix planning problem with outer-join ON clauses that reference
only the inner-side relation</para></listitem>
<listitem><para>Further fixes for <literal>x FULL JOIN y ON true</> corner
cases</para></listitem>
<listitem><para>Make <function>array_in</> and <function>array_recv</> more
paranoid about validating their OID parameter</para></listitem>
<listitem><para>Fix missing rows in queries like <literal>UPDATE a=... WHERE
a...</> with GiST index on column <literal>a</></para></listitem>
<listitem><para>Improve robustness of datetime parsing</para></listitem>
<listitem><para>Improve checking for partially-written WAL
pages</para></listitem>
<listitem><para>Improve robustness of signal handling when SSL is
enabled</para></listitem>
<listitem><para>Don't try to open more than <literal>max_files_per_process</>
files during postmaster startup</para></listitem>
<listitem><para>Various memory leakage fixes</para></listitem>
<listitem><para>Various portability improvements</para></listitem>
<listitem><para>Fix PL/pgSQL to handle <literal>var := var</> correctly when
the variable is of pass-by-reference type</para></listitem>
<listitem><para>Update <filename>contrib/tsearch2</> to use current Snowball
code</para></listitem>
</itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-8">
  <title>Release 7.4.8</title>

  <note>
  <title>Release Date</title>
  <simpara>2005-05-09</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 7.4.7, including several
   security-related issues.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>

  <sect2>
   <title>Migration to Version 7.4.8</title>

   <para>
    A dump/restore is not required for those running 7.4.X.  However,
    it is one possible way of handling two significant security problems
    that have been found in the initial contents of 7.4.X system
    catalogs.  A dump/initdb/reload sequence using 7.4.8's initdb will
    automatically correct these problems.
   </para>

   <para>
    The larger security problem is that the built-in character set encoding
    conversion functions can be invoked from SQL commands by unprivileged
    users, but the functions were not designed for such use and are not
    secure against malicious choices of arguments.  The fix involves changing
    the declared parameter list of these functions so that they can no longer
    be invoked from SQL commands.  (This does not affect their normal use
    by the encoding conversion machinery.)
   </para>

   <para>
    The lesser problem is that the <filename>contrib/tsearch2</> module
    creates several functions that are misdeclared to return
    <type>internal</> when they do not accept <type>internal</> arguments.
    This breaks type safety for all functions using <type>internal</>
    arguments.
   </para>

   <para>
    It is strongly recommended that all installations repair these errors,
    either by initdb or by following the manual repair procedures given
    below.  The errors at least allow unprivileged database users to crash
    their server process, and might allow unprivileged users to gain the
    privileges of a database superuser.
   </para>

   <para>
    If you wish not to do an initdb, perform the following procedures instead.
    As the database superuser, do:

<programlisting>
BEGIN;
UPDATE pg_proc SET proargtypes[3] = 'internal'::regtype
WHERE pronamespace = 11 AND pronargs = 5
     AND proargtypes[2] = 'cstring'::regtype;
-- The command should report having updated 90 rows;
-- if not, rollback and investigate instead of committing!
COMMIT;
</programlisting>

    Next, if you have installed <filename>contrib/tsearch2</>, do:

<programlisting>
BEGIN;
UPDATE pg_proc SET proargtypes[0] = 'internal'::regtype
WHERE oid IN (
   'dex_init(text)'::regprocedure,
   'snb_en_init(text)'::regprocedure,
   'snb_ru_init(text)'::regprocedure,
   'spell_init(text)'::regprocedure,
   'syn_init(text)'::regprocedure
);
-- The command should report having updated 5 rows;
-- if not, rollback and investigate instead of committing!
COMMIT;
</programlisting>

    If this command fails with a message like <quote>function
    "dex_init(text)" does not exist</>, then either <filename>tsearch2</>
    is not installed in this database, or you already did the update.
   </para>

   <para>
    The above procedures must be carried out in <emphasis>each</> database
    of an installation, including <literal>template1</>, and ideally
    including <literal>template0</> as well.  If you do not fix the
    template databases then any subsequently created databases will contain
    the same errors.  <literal>template1</> can be fixed in the same way
    as any other database, but fixing <literal>template0</> requires
    additional steps.  First, from any database issue:
<programlisting>
UPDATE pg_database SET datallowconn = true WHERE datname = 'template0';
</programlisting>
     Next connect to <literal>template0</> and perform the above repair
     procedures.  Finally, do:
<programlisting>
-- re-freeze template0:
VACUUM FREEZE;
-- and protect it against future alterations:
UPDATE pg_database SET datallowconn = false WHERE datname = 'template0';
</programlisting>
   </para>
  </sect2>

  <sect2>
   <title>Changes</title>

<itemizedlist>
<listitem><para>Change encoding function signature to prevent
misuse</para></listitem>
<listitem><para>Change <filename>contrib/tsearch2</> to avoid unsafe use of
<type>INTERNAL</> function results</para></listitem>
<listitem><para>Repair ancient race condition that allowed a transaction to be
seen as committed for some purposes (eg SELECT FOR UPDATE) slightly sooner
than for other purposes</para>
<para>This is an extremely serious bug since it could lead to apparent
data inconsistencies being briefly visible to applications.</para></listitem>
<listitem><para>Repair race condition between relation extension and
VACUUM</para>
<para>This could theoretically have caused loss of a page's worth of
freshly-inserted data, although the scenario seems of very low probability.
There are no known cases of it having caused more than an Assert failure.
</para></listitem>
<listitem><para>Fix comparisons of <type>TIME WITH TIME ZONE</> values</para>
<para>
The comparison code was wrong in the case where the
<literal>--enable-integer-datetimes</> configuration switch had been used.
NOTE: if you have an index on a <type>TIME WITH TIME ZONE</> column,
it will need to be <command>REINDEX</>ed after installing this update, because
the fix corrects the sort order of column values.
</para></listitem>
<listitem><para>Fix <function>EXTRACT(EPOCH)</> for
<type>TIME WITH TIME ZONE</> values</para></listitem>
<listitem><para>Fix mis-display of negative fractional seconds in
<type>INTERVAL</> values</para>
<para>
This error only occurred when the
<literal>--enable-integer-datetimes</> configuration switch had been used.
</para></listitem>
<listitem><para>Ensure operations done during backend shutdown are counted by
statistics collector</para>
<para>
This is expected to resolve reports of <application>pg_autovacuum</>
not vacuuming the system catalogs often enough &mdash; it was not being
told about catalog deletions caused by temporary table removal during
backend exit.
</para></listitem>
<listitem><para>Additional buffer overrun checks in plpgsql
(Neil)</para></listitem>
<listitem><para>Fix pg_dump to dump trigger names containing <literal>%</>
correctly (Neil)</para></listitem>
<listitem><para>Fix <filename>contrib/pgcrypto</> for newer OpenSSL builds
(Marko Kreen)</para></listitem>
<listitem><para>Still more 64-bit fixes for
<filename>contrib/intagg</></para></listitem>
<listitem><para>Prevent incorrect optimization of functions returning
<type>RECORD</></para></listitem>
<listitem><para>Prevent <function>to_char(interval)</> from dumping core for
month-related formats</para></listitem>
<listitem><para>Prevent crash on <literal>COALESCE(NULL,NULL)</></para></listitem>
<listitem><para>Fix <function>array_map</> to call PL functions correctly</para></listitem>
<listitem><para>Fix permission checking in <command>ALTER DATABASE RENAME</></para></listitem>
<listitem><para>Fix <command>ALTER LANGUAGE RENAME</></para></listitem>
<listitem><para>Make <function>RemoveFromWaitQueue</> clean up after itself</para>
<para>
This fixes a lock management error that would only be visible if a transaction
was kicked out of a wait for a lock (typically by query cancel) and then the
holder of the lock released it within a very narrow window.
</para></listitem>
<listitem><para>Fix problem with untyped parameter appearing in
<command>INSERT ... SELECT</></para></listitem>
<listitem><para>Fix <command>CLUSTER</> failure after
<command>ALTER TABLE SET WITHOUT OIDS</></para></listitem>
</itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-7">
  <title>Release 7.4.7</title>

  <note>
  <title>Release Date</title>
  <simpara>2005-01-31</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 7.4.6, including several
   security-related issues.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>

  <sect2>
   <title>Migration to Version 7.4.7</title>

   <para>
    A dump/restore is not required for those running 7.4.X.
   </para>
  </sect2>

  <sect2>
   <title>Changes</title>

<itemizedlist>
<listitem><para>Disallow <command>LOAD</> to non-superusers</para>
<para>
On platforms that will automatically execute initialization functions of a
shared library (this includes at least Windows and ELF-based Unixen),
<command>LOAD</> can be used to make the server execute arbitrary code.
Thanks to NGS Software for reporting this.</para></listitem>
<listitem><para>Check that creator of an aggregate function has the right to
execute the specified transition functions</para>
<para>
This oversight made it possible to bypass denial of EXECUTE
permission on a function.</para></listitem>
<listitem><para>Fix security and 64-bit issues in
contrib/intagg</para></listitem>
<listitem><para>Add needed STRICT marking to some contrib functions (Kris
Jurka)</para></listitem>
<listitem><para>Avoid buffer overrun when plpgsql cursor declaration has too
many parameters (Neil)</para></listitem>
<listitem><para>Fix planning error for FULL and RIGHT outer joins</para>
<para>
The result of the join was mistakenly supposed to be sorted the same as the
left input.  This could not only deliver mis-sorted output to the user, but
in case of nested merge joins could give outright wrong answers.
</para></listitem>
<listitem><para>Fix plperl for quote marks in tuple fields</para></listitem>
<listitem><para>Fix display of negative intervals in SQL and GERMAN
datestyles</para></listitem>
<listitem><para>Make age(timestamptz) do calculation in local timezone not
GMT</para></listitem>
</itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-6">
  <title>Release 7.4.6</title>

  <note>
  <title>Release Date</title>
  <simpara>2004-10-22</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 7.4.5.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>


  <sect2>
   <title>Migration to Version 7.4.6</title>

   <para>
    A dump/restore is not required for those running 7.4.X.
   </para>
  </sect2>

  <sect2>
   <title>Changes</title>

<itemizedlist>
<listitem><para>Repair possible failure to update hint bits on disk</para>
<para>
Under rare circumstances this oversight could lead to
<quote>could not access transaction status</> failures, which qualifies
it as a potential-data-loss bug.
</para></listitem>
<listitem><para>Ensure that hashed outer join does not miss tuples</para>
<para>
Very large left joins using a hash join plan could fail to output unmatched
left-side rows given just the right data distribution.
</para></listitem>
<listitem><para>Disallow running <application>pg_ctl</> as root</para>
<para>
This is to guard against any possible security issues.
</para></listitem>
<listitem><para>Avoid using temp files in <filename>/tmp</> in <command>make_oidjoins_check</command></para>
<para>
This has been reported as a security issue, though it's hardly worthy of
concern since there is no reason for non-developers to use this script anyway.
</para></listitem>
<listitem><para>Prevent forced backend shutdown from re-emitting prior command
result</para>
<para>
In rare cases, a client might think that its last command had succeeded when
it really had been aborted by forced database shutdown.
</para></listitem>
<listitem><para>Repair bug in <function>pg_stat_get_backend_idset</function></para>
<para>
This could lead to misbehavior in some of the system-statistics views.
</para></listitem>
<listitem><para>Fix small memory leak in postmaster</para></listitem>
<listitem><para>Fix <quote>expected both swapped tables to have TOAST
tables</> bug</para>
<para>
This could arise in cases such as CLUSTER after ALTER TABLE DROP COLUMN.
</para></listitem>
<listitem><para>Prevent <literal>pg_ctl restart</> from adding <literal>-D</> multiple times</para></listitem>
<listitem><para>Fix problem with NULL values in GiST indexes</para></listitem>
<listitem><para><literal>::</> is no longer interpreted as a variable in an
ECPG prepare statement</para></listitem>
</itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-5">
  <title>Release 7.4.5</title>

  <note>
  <title>Release Date</title>
  <simpara>2004-08-18</simpara>
  </note>

  <para>
   This release contains one serious bug fix over 7.4.4.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>


  <sect2>
   <title>Migration to Version 7.4.5</title>

   <para>
    A dump/restore is not required for those running 7.4.X.
   </para>
  </sect2>

  <sect2>
   <title>Changes</title>

<itemizedlist>
<listitem><para>Repair possible crash during concurrent B-tree index insertions</para>
<para>
This patch fixes a rare case in which concurrent insertions into a B-tree index
could result in a server panic.  No permanent damage would result, but it's
still worth a re-release.  The bug does not exist in pre-7.4 releases.
</para></listitem>
</itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-4">
  <title>Release 7.4.4</title>

  <note>
  <title>Release Date</title>
  <simpara>2004-08-16</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 7.4.3.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>


  <sect2>
   <title>Migration to Version 7.4.4</title>

   <para>
    A dump/restore is not required for those running 7.4.X.
   </para>
  </sect2>

  <sect2>
   <title>Changes</title>

<itemizedlist>
<listitem><para>Prevent possible loss of committed transactions during crash</para>
<para>
Due to insufficient interlocking between transaction commit and checkpointing,
it was possible for transactions committed just before the most recent
checkpoint to be lost, in whole or in part, following a database crash and
restart.  This is a serious bug that has existed
since <productname>PostgreSQL</productname> 7.1.
</para></listitem>
<listitem><para>Check HAVING restriction before evaluating result list of an
aggregate plan</para></listitem>
<listitem><para>Avoid crash when session's current user ID is deleted</para></listitem>
<listitem><para>Fix hashed crosstab for zero-rows case (Joe)</para></listitem>
<listitem><para>Force cache update after renaming a column in a foreign key</para></listitem>
<listitem><para>Pretty-print UNION queries correctly</para></listitem>
<listitem><para>Make psql handle <literal>\r\n</> newlines properly in COPY IN</para></listitem>
<listitem><para><application>pg_dump</> handled ACLs with grant options incorrectly</para></listitem>
<listitem><para>Fix thread support for macOS and Solaris</para></listitem>
<listitem><para>Updated JDBC driver (build 215) with various fixes</para></listitem>
<listitem><para>ECPG fixes</para></listitem>
<listitem><para>Translation updates (various contributors)</para></listitem>
</itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-3">
  <title>Release 7.4.3</title>

  <note>
  <title>Release Date</title>
  <simpara>2004-06-14</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 7.4.2.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>


  <sect2>
   <title>Migration to Version 7.4.3</title>

   <para>
    A dump/restore is not required for those running 7.4.X.
   </para>
  </sect2>

  <sect2>
   <title>Changes</title>

<itemizedlist>
<listitem><para>Fix temporary memory leak when using non-hashed aggregates (Tom)</para></listitem>
<listitem><para>ECPG fixes, including some for Informix compatibility (Michael)</para></listitem>
<listitem><para>Fixes for compiling with thread-safety, particularly Solaris (Bruce)</para></listitem>
<listitem><para>Fix error in COPY IN termination when using the old network protocol (ljb)</para></listitem>
<listitem><para>Several important fixes in pg_autovacuum, including fixes for
large tables, unsigned oids, stability, temp tables, and debug mode
(Matthew T. O'Connor)</para></listitem>
<listitem><para>Fix problem with reading tar-format dumps on NetBSD and BSD/OS (Bruce)</para></listitem>
<listitem><para>Several JDBC fixes</para></listitem>
<listitem><para>Fix ALTER SEQUENCE RESTART where last_value equals the restart value (Tom)</para></listitem>
<listitem><para>Repair failure to recalculate nested sub-selects (Tom)</para></listitem>
<listitem><para>Fix problems with non-constant expressions in LIMIT/OFFSET</para></listitem>
<listitem><para>Support FULL JOIN with no join clause, such as X FULL JOIN Y ON TRUE (Tom)</para></listitem>
<listitem><para>Fix another zero-column table bug (Tom)</para></listitem>
<listitem><para>Improve handling of non-qualified identifiers in GROUP BY clauses in sub-selects (Tom)</para>
<para>
Select-list aliases within the sub-select will now take precedence over
names from outer query levels.
</para></listitem>
<listitem><para>Do not generate <quote>NATURAL CROSS JOIN</> when decompiling rules (Tom)</para></listitem>
<listitem><para>Add checks for invalid field length in binary COPY (Tom)</para>
<para>
 This fixes a difficult-to-exploit security hole.
</para></listitem>
<listitem><para>Avoid locking conflict between <command>ANALYZE</command> and <command>LISTEN</command>/<command>NOTIFY</command></para></listitem>
<listitem><para>Numerous translation updates (various contributors)</para></listitem>
</itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-2">
  <title>Release 7.4.2</title>

  <note>
  <title>Release Date</title>
  <simpara>2004-03-08</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 7.4.1.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>


  <sect2>
   <title>Migration to Version 7.4.2</title>

   <para>
    A dump/restore is not required for those running 7.4.X.  However,
    it might be advisable as the easiest method of incorporating fixes for
    two errors that have been found in the initial contents of 7.4.X system
    catalogs.  A dump/initdb/reload sequence using 7.4.2's initdb will
    automatically correct these problems.
   </para>

   <para>
    The more severe of the two errors is that data type <type>anyarray</>
    has the wrong alignment label; this is a problem because the
    <structname>pg_statistic</> system catalog uses <type>anyarray</>
    columns.  The mislabeling can cause planner misestimations and even
    crashes when planning queries that involve <literal>WHERE</> clauses on
    double-aligned columns (such as <type>float8</> and <type>timestamp</>).
    It is strongly recommended that all installations repair this error,
    either by initdb or by following the manual repair procedure given
    below.
   </para>

   <para>
    The lesser error is that the system view <structname>pg_settings</>
    ought to be marked as having public update access, to allow
    <literal>UPDATE pg_settings</> to be used as a substitute for
    <command>SET</>.  This can also be fixed either by initdb or manually,
    but it is not necessary to fix unless you want to use <literal>UPDATE
    pg_settings</>.
   </para>

   <para>
    If you wish not to do an initdb, the following procedure will work
    for fixing <structname>pg_statistic</>.  As the database superuser,
    do:

<programlisting>
-- clear out old data in pg_statistic:
DELETE FROM pg_statistic;
VACUUM pg_statistic;
-- this should update 1 row:
UPDATE pg_type SET typalign = 'd' WHERE oid = 2277;
-- this should update 6 rows:
UPDATE pg_attribute SET attalign = 'd' WHERE atttypid = 2277;
--
-- At this point you MUST start a fresh backend to avoid a crash!
--
-- repopulate pg_statistic:
ANALYZE;
</programlisting>

    This can be done in a live database, but beware that all backends
    running in the altered database must be restarted before it is safe to
    repopulate <structname>pg_statistic</>.
   </para>

   <para>
    To repair the <structname>pg_settings</> error, simply do:
<programlisting>
GRANT SELECT, UPDATE ON pg_settings TO PUBLIC;
</programlisting>
   </para>

   <para>
    The above procedures must be carried out in <emphasis>each</> database
    of an installation, including <literal>template1</>, and ideally
    including <literal>template0</> as well.  If you do not fix the
    template databases then any subsequently created databases will contain
    the same errors.  <literal>template1</> can be fixed in the same way
    as any other database, but fixing <literal>template0</> requires
    additional steps.  First, from any database issue:
<programlisting>
UPDATE pg_database SET datallowconn = true WHERE datname = 'template0';
</programlisting>
     Next connect to <literal>template0</> and perform the above repair
     procedures.  Finally, do:
<programlisting>
-- re-freeze template0:
VACUUM FREEZE;
-- and protect it against future alterations:
UPDATE pg_database SET datallowconn = false WHERE datname = 'template0';
</programlisting>
   </para>
  </sect2>

  <sect2>
   <title>Changes</title>

<para>
   Release 7.4.2 incorporates all the fixes included in release 7.3.6,
   plus the following fixes:
</para>

<itemizedlist>
<listitem><para>Fix <structname>pg_statistic</> alignment bug that could crash optimizer</para>
<para>See above for details about this problem.</para></listitem>
<listitem><para>Allow non-super users to update <structname>pg_settings</></para></listitem>
<listitem><para>Fix several optimizer bugs, most of which led to
<quote>variable not found in subplan target lists</> errors</para></listitem>
<listitem><para>Avoid out-of-memory failure during startup of large multiple
index scan</para></listitem>
<listitem><para>Fix multibyte problem that could lead to <quote>out of
memory</> error during <command>COPY IN</></para></listitem>
<listitem><para>Fix problems with <command>SELECT INTO</> / <command>CREATE
TABLE AS</> from tables without OIDs</para></listitem>
<listitem><para>Fix problems with <filename>alter_table</> regression test
during parallel testing</para></listitem>
<listitem><para>Fix problems with hitting open file limit, especially on macOS (Tom)</para></listitem>
<listitem><para>Partial fix for Turkish-locale issues</para>
<para>initdb will succeed now in Turkish locale, but there are still some
inconveniences associated with the <literal>i/I</> problem.</para></listitem>
<listitem><para>Make pg_dump set client encoding on restore</para></listitem>
<listitem><para>Other minor pg_dump fixes</para></listitem>
<listitem><para>Allow ecpg to again use C keywords as column names (Michael)</para></listitem>
<listitem><para>Added ecpg <literal>WHENEVER NOT_FOUND</> to
<literal>SELECT/INSERT/UPDATE/DELETE</> (Michael)</para></listitem>
<listitem><para>Fix ecpg crash for queries calling set-returning functions (Michael)</para></listitem>
<listitem><para>Various other ecpg fixes (Michael)</para></listitem>
<listitem><para>Fixes for Borland compiler</para></listitem>
<listitem><para>Thread build improvements (Bruce)</para></listitem>
<listitem><para>Various other build fixes</para></listitem>
<listitem><para>Various JDBC fixes</para></listitem>
</itemizedlist>

  </sect2>
 </sect1>

 <sect1 id="release-7-4-1">
  <title>Release 7.4.1</title>

  <note>
  <title>Release Date</title>
  <simpara>2003-12-22</simpara>
  </note>

  <para>
   This release contains a variety of fixes from 7.4.
   For information about new features in the 7.4 major release, see
   <xref linkend="release-7-4">.
  </para>


  <sect2>
   <title>Migration to Version 7.4.1</title>

   <para>
    A dump/restore is <emphasis>not</emphasis> required for those
    running 7.4.
   </para>

   <para>
    If you want to install the fixes in the information schema
    you need to reload it into the database.
    This is either accomplished by initializing a new cluster
    by running <command>initdb</command>, or by running the following
    sequence of SQL commands in each database (ideally including
    <literal>template1</literal>) as a superuser in
    <application>psql</application>, after installing the new release:
<programlisting>
DROP SCHEMA information_schema CASCADE;
\i /usr/local/pgsql/share/information_schema.sql
</programlisting>
    Substitute your installation path in the second command.
   </para>

  </sect2>

  <sect2>
   <title>Changes</title>

<itemizedlist>
<listitem><para>Fixed bug in <command>CREATE SCHEMA</command> parsing in ECPG (Michael)</para></listitem>
<listitem><para>Fix compile error when <option>--enable-thread-safety</option> and <option>--with-perl</option> are used together (Peter)</para></listitem>
<listitem><para>Fix for subqueries that used hash joins (Tom)</para>
<para>
   Certain subqueries that used hash joins would crash because of
   improperly shared structures.
</para></listitem>
<listitem><para>Fix free space map compaction bug (Tom)</para>
<para>
   This fixes a bug where compaction of the free space map could lead
   to a database server shutdown.
</para>
</listitem>
<listitem><para>Fix for Borland compiler build of libpq (Bruce)</para></listitem>
<listitem><para>Fix <function>netmask()</function> and <function>hostmask()</function> to return the maximum-length masklen (Tom)</para>
<para>
   Fix these functions to return values consistent with pre-7.4
   releases.
</para>
</listitem>
<listitem><para>Several <filename>contrib/pg_autovacuum</filename> fixes</para>
<para>
   Fixes include improper variable initialization, missing vacuum after
   <command>TRUNCATE</command>, and duration computation overflow for long vacuums.
</para>
</listitem>
<listitem><para>Allow compile of <filename>contrib/cube</filename> under Cygwin (Jason Tishler)</para></listitem>
<listitem><para>Fix Solaris use of password file when no passwords are defined (Tom)</para>
<para>
   Fix crash on Solaris caused by use of any type of password
   authentication when no passwords were defined.
</para>
</listitem>
<listitem><para>JDBC fix for thread problems, other fixes</para></listitem>
<listitem><para>Fix for <type>bytea</type> index lookups (Joe)</para></listitem>
<listitem><para>Fix information schema for bit data types (Peter)</para></listitem>
<listitem><para>Force zero_damaged_pages to be on during recovery from WAL</para></listitem>
<listitem><para>Prevent some obscure cases of <quote>variable not in subplan target lists</quote></para></listitem>
<listitem><para>Make <function>PQescapeBytea</function> and <function>byteaout</function> consistent with each other (Joe)</para></listitem>
<listitem><para>Escape <type>bytea</type> output for bytes &gt; 0x7e(Joe)</para>
<para>
 If different client encodings are used for <type>bytea</type> output and input, it
 is possible for <type>bytea</type> values to be corrupted by the differing
 encodings.  This fix escapes all bytes that might be affected.
</para>
</listitem>
<listitem><para>Added missing <function>SPI_finish()</function> calls to dblink's <function>get_tuple_of_interest()</function> (Joe)</para></listitem>
<listitem><para>New Czech FAQ</para></listitem>
<listitem><para>Fix information schema view <literal>constraint_column_usage</literal> for foreign keys (Peter)</para></listitem>
<listitem><para>ECPG fixes (Michael)</para></listitem>
<listitem><para>Fix bug with multiple <literal>IN</literal> subqueries and joins in the subqueries (Tom)</para></listitem>
<listitem><para>Allow <literal>COUNT('x')</literal> to work (Tom)</para></listitem>
<listitem><para>Install ECPG include files for Informix compatibility into separate directory (Peter)</para>
<para>
 Some names of ECPG include files for Informix compatibility conflicted with operating system include files.
 By installing them in their own directory, name conflicts have been reduced.
</para>
</listitem>
<listitem><para>Fix SSL memory leak (Neil)</para>
<para>
 This release fixes a bug in 7.4 where SSL didn't free all memory it allocated.
</para>
</listitem>
<listitem><para>Prevent <filename>pg_service.conf</filename> from using service name as default dbname (Bruce)</para></listitem>
<listitem><para>Fix local ident authentication on FreeBSD (Tom)</para></listitem>
</itemizedlist>

 </sect2>
</sect1>

<sect1 id="release-7-4">
 <title>Release 7.4</title>

 <note>
  <title>Release Date</title>
  <simpara>2003-11-17</simpara>
 </note>

 <sect2>
  <title>Overview</title>

  <para>
   Major changes in this release:
  </para>

  <variablelist>
   <varlistentry>
    <term>
     <literal>IN</literal> / <literal>NOT IN</literal> subqueries are
     now much more efficient
    </term>

    <listitem>
     <para>
      In previous releases, <literal>IN</literal>/<literal>NOT
      IN</literal> subqueries were joined to the upper query by
      sequentially scanning the subquery looking for a match.  The
      7.4 code uses the same sophisticated techniques used by
      ordinary joins and so is much faster.  An
      <literal>IN</literal> will now usually be as fast as or faster
      than an equivalent <literal>EXISTS</literal> subquery; this
      reverses the conventional wisdom that applied to previous
      releases.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term>
     Improved <literal>GROUP BY</literal> processing by using hash buckets
    </term>

    <listitem>
     <para>
      In previous releases, rows to be grouped had to be sorted
      first.  The 7.4 code can do <literal>GROUP BY</literal>
      without sorting, by accumulating results into a hash table
      with one entry per group.  It will still use the sort
      technique, however, if the hash table is estimated to be too
      large to fit in <varname>sort_mem</>.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term>
     New multikey hash join capability
    </term>

    <listitem>
     <para>
      In previous releases, hash joins could only occur on single
      keys.  This release allows multicolumn hash joins.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term>
     Queries using the explicit <literal>JOIN</literal> syntax are
     now better optimized
    </term>

    <listitem>
     <para>
      Prior releases evaluated queries using the explicit
      <literal>JOIN</literal> syntax only in the order implied by
      the syntax. 7.4 allows full optimization of these queries,
      meaning the optimizer considers all possible join orderings
      and chooses the most efficient.  Outer joins, however, must
      still follow the declared ordering.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term>
     Faster and more powerful regular expression code
    </term>

    <listitem>
     <para>
      The entire regular expression module has been replaced with a
      new version by Henry Spencer, originally written for Tcl.  The
      code greatly improves performance and supports several flavors
      of regular expressions.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term>
     Function-inlining for simple SQL functions
    </term>

    <listitem>
     <para>
      Simple SQL functions can now be inlined by including their SQL
      in the main query.  This improves performance by eliminating
      per-call overhead.  That means simple SQL functions now
      behave like macros.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term>
     Full support for IPv6 connections and IPv6 address data types
    </term>

    <listitem>
     <para>
      Previous releases allowed only IPv4 connections, and the IP
      data types only supported IPv4 addresses. This release adds
      full IPv6 support in both of these areas.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term>
     Major improvements in SSL performance and reliability
    </term>

    <listitem>
     <para>
      Several people very familiar with the SSL API have overhauled
      our SSL code to improve SSL key negotiation and error
      recovery.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term>
     Make free space map efficiently reuse empty index pages,
     and other free space management improvements
    </term>

    <listitem>
     <para>
      In previous releases, B-tree index pages that were left empty
      because of deleted rows could only be reused by rows with
      index values similar to the rows originally indexed on that
      page. In 7.4, <command>VACUUM</command> records empty index
      pages and allows them to be reused for any future index rows.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term>
     SQL-standard information schema
    </term>

    <listitem>
     <para>
      The information schema provides a standardized and stable way
      to access information about the schema objects defined in a
      database.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term>
     Cursors conform more closely to the SQL standard
    </term>

    <listitem>
     <para>
      The commands <command>FETCH</command> and
      <command>MOVE</command> have been overhauled to conform more
      closely to the SQL standard.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term>
     Cursors can exist outside transactions
    </term>

    <listitem>
     <para>
      These cursors are also called holdable cursors.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term>
     New client-to-server protocol
    </term>

    <listitem>
     <para>
      The new protocol adds error codes, more status information,
      faster startup, better support for binary data transmission,
      parameter values separated from SQL commands, prepared
      statements available at the protocol level, and cleaner
      recovery from <command>COPY</command> failures.  The older
      protocol is still supported by both server and clients.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term>
     <application>libpq</application> and
     <application>ECPG</application> applications are now fully
     thread-safe
    </term>

    <listitem>
     <para>
      While previous <application>libpq</application> releases
      already supported threads, this release improves thread safety
      by fixing some non-thread-safe code that was used during
      database connection startup.  The <command>configure</command>
      option <option>--enable-thread-safety</option> must be used to
      enable this feature.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term>
     New version of full-text indexing
    </term>

    <listitem>
     <para>
      A new full-text indexing suite is available in
      <filename>contrib/tsearch2</filename>.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term>
     New autovacuum tool
    </term>

    <listitem>
     <para>
      The new autovacuum tool in
      <filename>contrib/autovacuum</filename> monitors the database
      statistics tables for
      <command>INSERT</command>/<command>UPDATE</command>/<command>DELETE</command>
      activity and automatically vacuums tables when needed.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term>
     Array handling has been improved and moved into the server core
    </term>

    <listitem>
     <para>
      Many array limitations have been removed, and arrays behave
      more like fully-supported data types.
     </para>
    </listitem>
   </varlistentry>

  </variablelist>
 </sect2>

 <sect2>
  <title>Migration to Version 7.4</title>

  <para>
   A dump/restore using <application>pg_dump</application> is
   required for those wishing to migrate data from any previous
   release.
  </para>

  <para>
   Observe the following incompatibilities:
  </para>

  <itemizedlist>
   <listitem>
    <para>
     The server-side autocommit setting was removed and
     reimplemented in client applications and languages.
     Server-side autocommit was causing too many problems with
     languages and applications that wanted to control their own
     autocommit behavior, so autocommit was removed from the server
     and added to individual client APIs as appropriate.
    </para>
   </listitem>

   <listitem>
    <para>
     Error message wording has changed substantially in this
     release.  Significant effort was invested to make the messages
     more consistent and user-oriented.  If your applications try to
     detect different error conditions by parsing the error message,
     you are strongly encouraged to use the new error code facility instead.
    </para>
   </listitem>

   <listitem>
    <para>
     Inner joins using the explicit <literal>JOIN</literal> syntax
     might behave differently because they are now better
     optimized.
    </para>
   </listitem>

   <listitem>
    <para>
     A number of server configuration parameters have been renamed
     for clarity, primarily those related to
     logging.
    </para>
   </listitem>

   <listitem>
    <para>
     <literal>FETCH 0</literal> or <literal>MOVE 0</literal> now
     does nothing.  In prior releases, <literal>FETCH 0</literal>
     would fetch all remaining rows, and <literal>MOVE 0</literal>
     would move to the end of the cursor.
    </para>
   </listitem>

   <listitem>
    <para>
     <command>FETCH</command> and <command>MOVE</command> now return
     the actual number of rows fetched/moved, or zero if at the
     beginning/end of the cursor.  Prior releases would return the
     row count passed to the command, not the number of rows
     actually fetched or moved.
    </para>
   </listitem>

   <listitem>
    <para>
     <command>COPY</command> now can process files that use
     carriage-return or carriage-return/line-feed end-of-line
     sequences. Literal carriage-returns and line-feeds are no
     longer accepted in data values; use <literal>\r</literal> and
     <literal>\n</literal> instead.
    </para>
   </listitem>

   <listitem>
    <para>
     Trailing spaces are now trimmed when converting from type
     <type>char(<replaceable>n</>)</type> to
     <type>varchar(<replaceable>n</>)</type> or <type>text</type>.
     This is what most people always expected to happen anyway.
    </para>
   </listitem>

   <listitem>
    <para>
     The data type <type>float(<replaceable>p</>)</type> now
     measures <replaceable>p</> in binary digits, not decimal
     digits.  The new behavior follows the SQL standard.
    </para>
   </listitem>

   <listitem>
    <para>
     Ambiguous date values now must match the ordering specified by
     the <varname>datestyle</varname> setting.  In prior releases, a
     date specification of <literal>10/20/03</> was interpreted as a
     date in October even if <varname>datestyle</> specified that
     the day should be first.  7.4 will throw an error if a date
     specification is invalid for the current setting of
     <varname>datestyle</>.
    </para>
   </listitem>

   <listitem>
    <para>
     The functions <function>oidrand</function>,
     <function>oidsrand</function>, and
     <function>userfntest</function> have been removed.  These
     functions were determined to be no longer useful.
    </para>
   </listitem>

   <listitem>
    <para>
     String literals specifying time-varying date/time values, such
     as <literal>'now'</literal> or <literal>'today'</literal> will
     no longer work as expected in column default expressions; they
     now cause the time of the table creation to be the default, not
     the time of the insertion.  Functions such as
     <function>now()</>, <function>current_timestamp</>, or
     <function>current_date</function> should be used instead.
    </para>

    <para>
     In previous releases, there was special code so that strings
     such as <literal>'now'</literal> were interpreted at
     <command>INSERT</> time and not at table creation time, but
     this work around didn't cover all cases.  Release 7.4 now
     requires that defaults be defined properly using functions such
     as <function>now()</> or <function>current_timestamp</>. These
     will work in all situations.
    </para>
   </listitem>

   <listitem>
    <para>
     The dollar sign (<literal>$</>) is no longer allowed in
     operator names.  It can instead be a non-first character in
     identifiers.  This was done to improve compatibility with other
     database systems, and to avoid syntax problems when parameter
     placeholders (<literal>$<replaceable>n</></>) are written
     adjacent to operators.
    </para>
   </listitem>

  </itemizedlist>
 </sect2>

 <sect2>
  <title>Changes</title>

  <para>
   Below you will find a detailed account of the changes between
   release 7.4 and the previous major release.
  </para>

 <sect3>
  <title>Server Operation Changes</title>

  <itemizedlist>
   <listitem>
    <para>
     Allow IPv6 server connections (Nigel Kukard, Johan Jordaan,
     Bruce, Tom, Kurt Roeckx, Andrew Dunstan)
    </para>
   </listitem>

   <listitem>
    <para>
     Fix SSL to handle errors cleanly (Nathan Mueller)
    </para>
    <para>
     In prior releases, certain SSL API error reports were not
     handled correctly.  This release fixes those problems.
    </para>
   </listitem>

   <listitem>
    <para>
     SSL protocol security and performance improvements (Sean Chittenden)
    </para>
    <para>
     SSL key renegotiation was happening too frequently, causing poor
     SSL performance.  Also, initial key handling was improved.
    </para>
   </listitem>

   <listitem>
    <para>
     Print lock information when a deadlock is detected (Tom)
    </para>
    <para>
     This allows easier debugging of deadlock situations.
    </para>
   </listitem>

   <listitem>
    <para>
     Update <filename>/tmp</filename> socket modification times
     regularly to avoid their removal (Tom)
    </para>
    <para>
     This should help prevent <filename>/tmp</filename> directory
     cleaner administration scripts from removing server socket
     files.
    </para>
   </listitem>

   <listitem><para>Enable PAM for macOS (Aaron Hillegass)</para></listitem>

   <listitem>
    <para>Make B-tree indexes fully WAL-safe (Tom)</para>
    <para>
     In prior releases, under certain rare cases, a server crash
     could cause B-tree indexes to become corrupt. This release
     removes those last few rare cases.
    </para>
   </listitem>

   <listitem><para>Allow B-tree index compaction and empty page reuse (Tom)</para></listitem>

   <listitem>
    <para>
     Fix inconsistent index lookups during split of first root page (Tom)
    </para>
    <para>
     In prior releases, when a single-page index split into two
     pages, there was a brief period when another database session
     could miss seeing an index entry.  This release fixes that rare
     failure case.
    </para>
   </listitem>

   <listitem><para>Improve free space map allocation logic (Tom)</para></listitem>

   <listitem>
    <para>Preserve free space information between server restarts (Tom)</para>
    <para>
     In prior releases, the free space map was not saved when the
     postmaster was stopped, so newly started servers had no free
     space information. This release saves the free space map, and
     reloads it when the server is restarted.
    </para>
   </listitem>

   <listitem><para>Add start time to <literal>pg_stat_activity</literal> (Neil)</para></listitem>
   <listitem><para>New code to detect corrupt disk pages; erase with <varname>zero_damaged_pages</varname> (Tom)</para></listitem>
   <listitem><para>New client/server protocol: faster, no username length limit, allow clean exit from <command>COPY</command> (Tom)</para></listitem>
   <listitem><para>Add transaction status, table ID, column ID to client/server protocol (Tom)</para></listitem>
   <listitem><para>Add binary I/O to client/server protocol (Tom)</para></listitem>
   <listitem><para>Remove autocommit server setting; move to client applications (Tom)</para></listitem>
   <listitem><para>New error message wording, error codes, and three levels of error detail (Tom, Joe, Peter)</para></listitem>
  </itemizedlist>
 </sect3>

 <sect3>
  <title>Performance Improvements</title>

  <itemizedlist>
   <listitem><para>Add hashing for <literal>GROUP BY</literal> aggregates (Tom)</para></listitem>
   <listitem><para>Make nested-loop joins be smarter about multicolumn indexes (Tom)</para></listitem>
   <listitem><para>Allow multikey hash joins (Tom)</para></listitem>
   <listitem><para>Improve constant folding (Tom)</para></listitem>
   <listitem><para>Add ability to inline simple SQL functions (Tom)</para></listitem>

   <listitem>
    <para>Reduce memory usage for queries using complex functions (Tom)</para>
    <para>
     In prior releases, functions returning allocated memory would
     not free it until the query completed. This release allows the
     freeing of function-allocated memory when the function call
     completes, reducing the total memory used by functions.
    </para>
   </listitem>

   <listitem>
    <para>Improve GEQO optimizer performance (Tom)</para>
    <para>
     This release fixes several inefficiencies in the way the GEQO optimizer
     manages potential query paths.
    </para>
   </listitem>

   <listitem>
    <para>
     Allow <literal>IN</>/<literal>NOT IN</> to be handled via hash
     tables (Tom)
    </para>
   </listitem>

   <listitem>
    <para>
     Improve <literal>NOT IN (<replaceable>subquery</>)</literal>
     performance (Tom)
    </para>
   </listitem>

   <listitem>
    <para>
     Allow most <literal>IN</literal> subqueries to be processed as
     joins (Tom)
    </para>
   </listitem>

   <listitem>
    <para>
     Pattern matching operations can use indexes regardless of
     locale (Peter)
    </para>
    <para>
     There is no way for non-ASCII locales to use the standard
     indexes for <literal>LIKE</literal> comparisons. This release
     adds a way to create a special index for
     <literal>LIKE</literal>.
    </para>
   </listitem>

   <listitem>
    <para>Allow the postmaster to preload libraries using <varname>preload_libraries</varname> (Joe)</para>
    <para>
     For shared libraries that require a long time to load, this
     option is available so the library can be preloaded in the
     postmaster and inherited by all database sessions.
    </para>
   </listitem>

   <listitem>
    <para>
     Improve optimizer cost computations, particularly for subqueries (Tom)
    </para>
   </listitem>

   <listitem>
    <para>
     Avoid sort when subquery <literal>ORDER BY</literal> matches upper query (Tom)
    </para>
   </listitem>

   <listitem>
    <para>
     Deduce that <literal>WHERE a.x = b.y AND b.y = 42</literal> also
     means <literal>a.x = 42</literal> (Tom)
    </para>
   </listitem>

   <listitem>
    <para>
     Allow hash/merge joins on complex joins (Tom)
    </para>
   </listitem>

   <listitem>
    <para>
     Allow hash joins for more data types (Tom)
    </para>
   </listitem>

   <listitem>
    <para>
     Allow join optimization of explicit inner joins, disable with
     <varname>join_collapse_limit</varname> (Tom)
    </para>
   </listitem>

   <listitem>
    <para>
     Add parameter <varname>from_collapse_limit</varname> to control
     conversion of subqueries to joins (Tom)
    </para>
   </listitem>

   <listitem>
    <para>
     Use faster and more powerful regular expression code from Tcl
     (Henry Spencer, Tom)
    </para>
   </listitem>

   <listitem>
    <para>
     Use bit-mapped relation sets in the optimizer (Tom)
    </para>
   </listitem>

   <listitem>
    <para>Improve connection startup time (Tom)</para>
    <para>
     The new client/server protocol requires fewer network packets to
     start a database session.
    </para>
   </listitem>

   <listitem>
    <para>
     Improve trigger/constraint performance (Stephan)
    </para>
   </listitem>

   <listitem>
    <para>
     Improve speed of <literal>col IN (const, const, const, ...)</literal> (Tom)
    </para>
   </listitem>

   <listitem>
    <para>
     Fix hash indexes which were broken in rare cases (Tom)
    </para>
   </listitem>

   <listitem><para>Improve hash index concurrency and speed (Tom)</para>
    <para>
     Prior releases suffered from poor hash index performance,
     particularly for high concurrency situations. This release fixes
     that, and the development group is interested in reports
     comparing B-tree and hash index performance.
    </para>
   </listitem>

   <listitem>
    <para>Align shared buffers on 32-byte boundary for copy speed improvement (Manfred Spraul)</para>
    <para>
     Certain CPU's perform faster data copies when addresses are
     32-byte aligned.
    </para>
   </listitem>

   <listitem>
    <para>Data type <type>numeric</type> reimplemented for better performance (Tom)</para>
    <para>
     <type>numeric</type> used to be stored in base 100. The new code
     uses base 10000, for significantly better performance.
    </para>
   </listitem>
  </itemizedlist>
 </sect3>

 <sect3>
  <title>Server Configuration Changes</title>

  <itemizedlist>
   <listitem>
    <para>Rename server parameter <varname>server_min_messages</> to <varname>log_min_messages</> (Bruce)</para>
    <para>
     This was done so most parameters that control the server logs
     begin with <literal>log_</>.
    </para>
   </listitem>

   <listitem><para>Rename <varname>show_*_stats</> to <varname>log_*_stats</> (Bruce)</para></listitem>
   <listitem><para>Rename <varname>show_source_port</> to <varname>log_source_port</> (Bruce)</para></listitem>
   <listitem><para>Rename <varname>hostname_lookup</> to <varname>log_hostname</> (Bruce)</para></listitem>

   <listitem>
    <para>Add <varname>checkpoint_warning</> to warn of excessive checkpointing (Bruce)</para>
    <para>
     In prior releases, it was difficult to determine if checkpoint
     was happening too frequently. This feature adds a warning to the
     server logs when excessive checkpointing happens.
    </para>
   </listitem>

   <listitem><para>New read-only server parameters for localization (Tom)</para></listitem>

   <listitem>
    <para>
     Change debug server log messages to output as <literal>DEBUG</>
     rather than <literal>LOG</> (Bruce)
    </para>
   </listitem>

   <listitem>
    <para>Prevent server log variables from being turned off by non-superusers (Bruce)</para>
    <para>
     This is a security feature so non-superusers cannot disable
     logging that was enabled by the administrator.
    </para>
   </listitem>

   <listitem>
    <para>
     <varname>log_min_messages</>/<varname>client_min_messages</> now
     controls <varname>debug_*</> output (Bruce)
    </para>
    <para>
     This centralizes client debug information so all debug output
     can be sent to either the client or server logs.
    </para>
   </listitem>

   <listitem>
    <para>Add macOS Rendezvous server support (Chris Campbell)</para>
    <para>
     This allows macOS hosts to query the network for available
     <productname>PostgreSQL</productname> servers.
    </para>
   </listitem>

   <listitem>
    <para>
     Add ability to print only slow statements using
     <varname>log_min_duration_statement</varname>
     (Christopher)
    </para>
    <para>
     This is an often requested debugging feature that allows
     administrators to see only slow queries in their server logs.
    </para>
   </listitem>

   <listitem>
    <para>Allow <filename>pg_hba.conf</filename> to accept netmasks in CIDR format (Andrew Dunstan)</para>
    <para>
     This allows administrators to merge the host IP address and
     netmask fields into a single CIDR field in <filename>pg_hba.conf</filename>.
    </para>
   </listitem>

   <listitem><para>New read-only parameter <varname>is_superuser</varname> (Tom)</para></listitem>

   <listitem>
    <para>New parameter <varname>log_error_verbosity</varname> to control error detail (Tom)</para>
    <para>
     This works with the new error reporting feature to supply
     additional error information like hints, file names and line
     numbers.
    </para>
   </listitem>

   <listitem>
    <para><literal>postgres --describe-config</literal> now dumps server config variables (Aizaz Ahmed, Peter)</para>
    <para>
     This option is useful for administration tools that need to know
     the configuration variable names and their minimums, maximums,
     defaults, and descriptions.
    </para>
   </listitem>

   <listitem>
    <para>
     Add new columns in <literal>pg_settings</literal>:
     <literal>context</>, <literal>type</>, <literal>source</>,
     <literal>min_val</>, <literal>max_val</> (Joe)
    </para>
   </listitem>

   <listitem>
    <para>
     Make default <varname>shared_buffers</> 1000 and
     <varname>max_connections</> 100, if possible (Tom)
    </para>
    <para>
     Prior versions defaulted to 64 shared buffers so <productname>PostgreSQL</productname>
     would start on even very old systems. This release tests the
     amount of shared memory allowed by the platform and selects more
     reasonable default values if possible.  Of course, users are
     still encouraged to evaluate their resource load and size
     <varname>shared_buffers</varname> accordingly.
    </para>
   </listitem>

   <listitem>
    <para>
     New <filename>pg_hba.conf</filename> record type
     <literal>hostnossl</> to prevent SSL connections (Jon
     Jensen)
    </para>
    <para>
     In prior releases, there was no way to prevent SSL connections
     if both the client and server supported SSL. This option allows
     that capability.
    </para>
   </listitem>

   <listitem>
    <para>
     Remove parameter <varname>geqo_random_seed</varname>
     (Tom)
    </para>
   </listitem>

   <listitem>
    <para>
     Add server parameter <varname>regex_flavor</varname> to control regular expression processing (Tom)
    </para>
   </listitem>

   <listitem>
    <para>
     Make <command>pg_ctl</command> better handle nonstandard ports (Greg)
    </para>
   </listitem>
  </itemizedlist>
 </sect3>

 <sect3>
  <title>Query Changes</title>

  <itemizedlist>
   <listitem><para>New SQL-standard information schema (Peter)</para></listitem>
   <listitem><para>Add read-only transactions (Peter)</para></listitem>
   <listitem><para>Print key name and value in foreign-key violation messages (Dmitry Tkach)</para></listitem>

   <listitem>
    <para>Allow users to see their own queries in <literal>pg_stat_activity</literal> (Kevin Brown)</para>
    <para>
     In prior releases, only the superuser could see query strings
     using <literal>pg_stat_activity</literal>. Now ordinary users
     can see their own query strings.
    </para>
   </listitem>

   <listitem>
    <para>Fix aggregates in subqueries to match SQL standard (Tom)</para>
    <para>
     The SQL standard says that an aggregate function appearing
     within a nested subquery belongs to the outer query if its
     argument contains only outer-query variables.  Prior
     <productname>PostgreSQL</productname> releases did not handle
     this fine point correctly.
    </para>
   </listitem>

   <listitem>
    <para>Add option to prevent auto-addition of tables referenced in query (Nigel J. Andrews)</para>
    <para>
     By default, tables mentioned in the query are automatically
     added to the <literal>FROM</> clause if they are not already
     there.  This is compatible with historic
     <productname>POSTGRES</productname> behavior but is contrary to
     the SQL standard.  This option allows selecting
     standard-compatible behavior.
    </para>
   </listitem>

   <listitem>
    <para>Allow <literal>UPDATE ... SET col = DEFAULT</literal> (Rod)</para>
    <para>
     This allows <command>UPDATE</command> to set a column to its
     declared default value.
    </para>
   </listitem>

   <listitem>
    <para>Allow expressions to be used in <literal>LIMIT</>/<literal>OFFSET</> (Tom)</para>
    <para>
     In prior releases, <literal>LIMIT</>/<literal>OFFSET</> could
     only use constants, not expressions.
    </para>
   </listitem>

   <listitem>
    <para>Implement <literal>CREATE TABLE AS EXECUTE</literal> (Neil, Peter)</para>
   </listitem>
  </itemizedlist>
 </sect3>

 <sect3>
  <title>Object Manipulation Changes</title>

  <itemizedlist>
   <listitem>
    <para>Make <command>CREATE SEQUENCE</command> grammar more conforming to SQL:2003 (Neil)</para>
   </listitem>

   <listitem>
    <para>Add statement-level triggers (Neil)</para>
    <para>
     While this allows a trigger to fire at the end of a statement,
     it does not allow the trigger to access all rows modified by the
     statement.  This capability is planned for a future release.
    </para>
   </listitem>

   <listitem>
    <para>Add check constraints for domains (Rod)</para>
    <para>
     This greatly increases the usefulness of domains by allowing
     them to use check constraints.
    </para>
   </listitem>

   <listitem>
    <para>Add <command>ALTER DOMAIN</command> (Rod)</para>
    <para>
     This allows manipulation of existing domains.
    </para>
   </listitem>

   <listitem>
    <para>Fix several zero-column table bugs (Tom)</para>
    <para>
     <productname>PostgreSQL</productname> supports zero-column tables. This fixes various bugs
     that occur when using such tables.
    </para>
   </listitem>

   <listitem>
    <para>Have <literal>ALTER TABLE ... ADD PRIMARY KEY</literal> add not-null constraint (Rod)</para>
    <para>
     In prior releases, <literal>ALTER TABLE ... ADD
     PRIMARY</literal> would add a unique index, but not a not-null
     constraint.  That is fixed in this release.
    </para>
   </listitem>

   <listitem><para>Add <literal>ALTER TABLE ... WITHOUT OIDS</literal> (Rod)</para>
    <para>
     This allows control over whether new and updated rows will have
     an OID column.  This is most useful for saving storage space.
    </para>
   </listitem>

   <listitem>
    <para>
     Add <literal>ALTER SEQUENCE</literal> to modify minimum, maximum,
     increment, cache, cycle values (Rod)
    </para>
   </listitem>

   <listitem>
    <para>Add <literal>ALTER TABLE ... CLUSTER ON</literal> (Alvaro Herrera)</para>
    <para>
     This command is used by <command>pg_dump</command> to record the
     cluster column for each table previously clustered. This
     information is used by database-wide cluster to cluster all
     previously clustered tables.
    </para>
   </listitem>

   <listitem><para>Improve automatic type casting for domains (Rod, Tom)</para></listitem>
   <listitem><para>Allow dollar signs in identifiers, except as first character (Tom)</para></listitem>
   <listitem><para>Disallow dollar signs in operator names, so <literal>x=$1</> works (Tom)</para></listitem>

   <listitem>
    <para>
     Allow copying table schema using <literal>LIKE
     <replaceable>subtable</replaceable></literal>, also SQL:2003
     feature <literal>INCLUDING DEFAULTS</literal> (Rod)
    </para>
   </listitem>

   <listitem>
    <para>
     Add <literal>WITH GRANT OPTION</literal> clause to
     <command>GRANT</command> (Peter)
    </para>
    <para>
     This enabled <command>GRANT</command> to give other users the
     ability to grant privileges on an object.
    </para>
   </listitem>
  </itemizedlist>
 </sect3>

 <sect3>
  <title>Utility Command Changes</title>

  <itemizedlist>
   <listitem>
    <para>Add <literal>ON COMMIT</literal> clause to <command>CREATE TABLE</command> for temporary tables (Gavin)</para>
    <para>
     This adds the ability for a table to be dropped or all rows
     deleted on transaction commit.
    </para>
   </listitem>

   <listitem>
    <para>Allow cursors outside transactions using <literal>WITH HOLD</literal> (Neil)</para>
    <para>
     In previous releases, cursors were removed at the end of the
     transaction that created them. Cursors can now be created with
     the <literal>WITH HOLD</literal> option, which allows them to
     continue to be accessed after the creating transaction has
     committed.
    </para>
   </listitem>

   <listitem>
    <para><literal>FETCH 0</literal> and <literal>MOVE 0 </literal> now do nothing (Bruce)</para>
    <para>
     In previous releases, <literal>FETCH 0</literal> fetched all
     remaining rows, and <literal>MOVE 0</literal> moved to the end
     of the cursor.
    </para>
   </listitem>

   <listitem>
    <para>
     Cause <command>FETCH</command> and <command>MOVE</command> to
     return the number of rows fetched/moved, or zero if at the
     beginning/end of cursor, per SQL standard (Bruce)
    </para>
    <para>
     In prior releases, the row count returned by
     <command>FETCH</command> and <command>MOVE</command> did not
     accurately reflect the number of rows processed.
    </para>
   </listitem>

   <listitem>
    <para>Properly handle <literal>SCROLL</literal> with cursors, or
    report an error (Neil)</para>
    <para>
     Allowing random access (both forward and backward scrolling) to
     some kinds of queries cannot be done without some additional
     work. If <literal>SCROLL</literal> is specified when the cursor
     is created, this additional work will be performed. Furthermore,
     if the cursor has been created with <literal>NO SCROLL</literal>,
     no random access is allowed.
    </para>
   </listitem>

   <listitem>
    <para>
     Implement SQL-compatible options <literal>FIRST</>,
     <literal>LAST</>, <literal>ABSOLUTE <replaceable>n</></>,
     <literal>RELATIVE <replaceable>n</></> for
     <command>FETCH</command> and <command>MOVE</command> (Tom)
    </para>
   </listitem>

   <listitem>
    <para>Allow <command>EXPLAIN</command> on <command>DECLARE CURSOR</command> (Tom)</para>
   </listitem>

   <listitem>
    <para>Allow <command>CLUSTER</command> to use index marked as pre-clustered by default (Alvaro Herrera)</para>
   </listitem>

   <listitem>
    <para>Allow <command>CLUSTER</command> to cluster all tables (Alvaro Herrera)</para>
    <para>
     This allows all previously clustered tables in a database to be
     reclustered with a single command.
    </para>
   </listitem>

   <listitem><para>Prevent <command>CLUSTER</command> on partial indexes (Tom)</para></listitem>

   <listitem><para>Allow DOS and Mac line-endings in <command>COPY</> files (Bruce)</para></listitem>

   <listitem>
    <para>
     Disallow literal carriage return as a data value,
     backslash-carriage-return and <literal>\r</> are still allowed
     (Bruce)
    </para>
   </listitem>

   <listitem>
    <para><command>COPY</> changes (binary, <literal>\.</>) (Tom)</para>
   </listitem>

   <listitem>
    <para>Recover from <command>COPY</command> failure cleanly (Tom)</para>
   </listitem>

   <listitem>
    <para>Prevent possible memory leaks in <command>COPY</command> (Tom)</para>
   </listitem>

   <listitem>
    <para>Make <command>TRUNCATE</command> transaction-safe (Rod)</para>
    <para>
     <command>TRUNCATE</command> can now be used inside a
     transaction. If the transaction aborts, the changes made by the
     <command>TRUNCATE</command> are automatically rolled back.
    </para>
   </listitem>

   <listitem>
    <para>
     Allow prepare/bind of utility commands like
     <command>FETCH</command> and <command>EXPLAIN</command> (Tom)
    </para>
   </listitem>

   <listitem>
    <para>Add <command>EXPLAIN EXECUTE</command> (Neil)</para>
   </listitem>

   <listitem>
    <para>Improve <command>VACUUM</command> performance on indexes by reducing WAL traffic (Tom)</para>
   </listitem>

   <listitem>
    <para>Functional indexes have been generalized into indexes on expressions (Tom)</para>
    <para>
     In prior releases, functional indexes only supported a simple
     function applied to one or more column names.  This release
     allows any type of scalar expression.
    </para>
   </listitem>

   <listitem>
    <para>
     Have <command>SHOW TRANSACTION ISOLATION</command> match input
     to <command>SET TRANSACTION ISOLATION</command>
     (Tom)
    </para>
   </listitem>

   <listitem>
    <para>
      Have <command>COMMENT ON DATABASE</command> on nonlocal
      database generate a warning, rather than an error (Rod)
     </para>

    <para>
     Database comments are stored in database-local tables so
     comments on a database have to be stored in each database.
    </para>
   </listitem>

   <listitem>
    <para>
     Improve reliability of <command>LISTEN</>/<command>NOTIFY</> (Tom)
    </para>
   </listitem>

   <listitem>
    <para>Allow <command>REINDEX</command> to reliably reindex nonshared system catalog indexes (Tom)</para>
    <para>
     This allows system tables to be reindexed without the
     requirement of a standalone session, which was necessary in
     previous releases. The only tables that now require a standalone
     session for reindexing are the global system tables
     <literal>pg_database</>, <literal>pg_shadow</>, and
     <literal>pg_group</>.
    </para>
   </listitem>
  </itemizedlist>
 </sect3>

 <sect3>
  <title>Data Type and Function Changes</title>

  <itemizedlist>
   <listitem>
    <para>
     New server parameter <varname>extra_float_digits</varname> to
     control precision display of floating-point numbers (Pedro
     Ferreira, Tom)
    </para>
    <para>
     This controls output precision which was causing regression
     testing problems.
    </para>
   </listitem>

   <listitem><para>Allow <literal>+1300</literal> as a numeric time-zone specifier, for FJST (Tom)</para></listitem>

   <listitem>
    <para>
     Remove rarely used functions <function>oidrand</>,
     <function>oidsrand</>, and <function>userfntest</> functions
     (Neil)
    </para>
   </listitem>

   <listitem>
    <para>Add <function>md5()</> function to main server, already in <filename>contrib/pgcrypto</filename> (Joe)</para>
    <para>
     An MD5 function was frequently requested. For more complex
     encryption capabilities, use
     <filename>contrib/pgcrypto</filename>.
    </para>
   </listitem>

   <listitem><para>Increase date range of <type>timestamp</type> (John Cochran)</para></listitem>

   <listitem>
    <para>
     Change <literal>EXTRACT(EPOCH FROM timestamp)</literal> so
     <type>timestamp without time zone</type> is assumed to be in
     local time, not GMT (Tom)
    </para>
   </listitem>

   <listitem><para>Trap division by zero in case the operating system doesn't prevent it (Tom)</para></listitem>
   <listitem><para>Change the <type>numeric</type> data type internally to base 10000 (Tom)</para></listitem>
   <listitem><para>New <function>hostmask()</function> function (Greg Wickham)</para></listitem>
   <listitem><para>Fixes for <function>to_char()</function> and <function>to_timestamp()</function> (Karel)</para></listitem>

   <listitem>
    <para>
     Allow functions that can take any argument data type and return
     any data type, using <type>anyelement</type> and
     <type>anyarray</type> (Joe)
    </para>
    <para>
     This allows the creation of functions that can work with any
     data type.
    </para>
   </listitem>

   <listitem>
    <para>
     Arrays can now be specified as <literal>ARRAY[1,2,3]</literal>,
     <literal>ARRAY[['a','b'],['c','d']]</literal>, or
     <literal>ARRAY[ARRAY[ARRAY[2]]]</literal> (Joe)
    </para>
   </listitem>

   <listitem>
    <para>
     Allow proper comparisons for arrays, including <literal>ORDER
     BY</literal> and <literal>DISTINCT</literal> support
     (Joe)
    </para>
   </listitem>

   <listitem><para>Allow indexes on array columns (Joe)</para></listitem>
   <listitem><para>Allow array concatenation with <literal>||</literal> (Joe)</para></listitem>

   <listitem>
    <para>
     Allow <literal>WHERE</literal> qualification
     <literal><replaceable>expr</> <replaceable>op</> ANY/SOME/ALL
     (<replaceable>array_expr</>)</literal> (Joe)
    </para>
    <para>
     This allows arrays to behave like a list of values, for purposes
     like <literal>SELECT * FROM tab WHERE col IN
     (array_val)</literal>.
    </para>
   </listitem>

   <listitem>
    <para>
     New array functions <function>array_append</>,
     <function>array_cat</>, <function>array_lower</>,
     <function>array_prepend</>, <function>array_to_string</>,
     <function>array_upper</>, <function>string_to_array</> (Joe)
    </para>
   </listitem>

   <listitem><para>Allow user defined aggregates to use polymorphic functions (Joe)</para></listitem>
   <listitem><para>Allow assignments to empty arrays (Joe)</para></listitem>

   <listitem>
    <para>
     Allow 60 in seconds fields of <type>time</type>,
     <type>timestamp</type>, and <type>interval</type> input values
     (Tom)
    </para>
    <para>
     Sixty-second values are needed for leap seconds.
    </para>
   </listitem>

   <listitem><para>Allow <type>cidr</type> data type to be cast to <type>text</type> (Tom)</para></listitem>

   <listitem><para>Disallow invalid time zone names in SET TIMEZONE</para></listitem>

   <listitem>
    <para>
     Trim trailing spaces when <type>char</type> is cast to
     <type>varchar</> or <type>text</> (Tom)
    </para>
   </listitem>

   <listitem>
    <para>
     Make <type>float(<replaceable>p</>)</> measure the precision
     <replaceable>p</> in binary digits, not decimal digits
     (Tom)
    </para>
   </listitem>

   <listitem>
    <para>Add IPv6 support to the <type>inet</type> and <type>cidr</type> data types (Michael Graff)</para>
   </listitem>

   <listitem>
    <para>Add <function>family()</function> function to report whether address is IPv4 or IPv6 (Michael Graff)</para>
   </listitem>

   <listitem>
    <para>
     Have <literal>SHOW datestyle</literal> generate output similar
     to that used by <literal>SET datestyle</literal> (Tom)
    </para>
   </listitem>

   <listitem>
    <para>
     Make <literal>EXTRACT(TIMEZONE)</literal> and <literal>SET/SHOW
     TIME ZONE</literal> follow the SQL convention for the sign of
     time zone offsets, i.e., positive is east from UTC (Tom)
    </para>
   </listitem>

   <listitem>
    <para>Fix <literal>date_trunc('quarter', ...)</literal> (B&ouml;jthe Zolt&aacute;n)</para>
    <para>
     Prior releases returned an incorrect value for this function call.
    </para>
   </listitem>

   <listitem>
    <para>Make <function>initcap()</function> more compatible with Oracle (Mike Nolan)</para>
    <para>
     <function>initcap()</function> now uppercases a letter appearing
     after any non-alphanumeric character, rather than only after
     whitespace.
    </para>
   </listitem>

   <listitem>
    <para>Allow only <varname>datestyle</varname> field order for date values not in ISO-8601 format (Greg)</para>
   </listitem>

   <listitem>
    <para>
     Add new <varname>datestyle</varname> values <literal>MDY</>,
     <literal>DMY</>, and <literal>YMD</> to set input field order;
     honor <literal>US</> and <literal>European</> for backward
     compatibility (Tom)
    </para>
   </listitem>

   <listitem>
    <para>
     String literals like <literal>'now'</literal> or
     <literal>'today'</literal> will no longer work as a column
     default. Use functions such as <function>now()</function>,
     <function>current_timestamp</function> instead.  (change
     required for prepared statements) (Tom)
    </para>
   </listitem>

   <listitem>
    <para>Treat NaN as larger than any other value in <function>min()</>/<function>max()</> (Tom)</para>
    <para>
     NaN was already sorted after ordinary numeric values for most
     purposes, but <function>min()</> and <function>max()</> didn't
     get this right.
    </para>
   </listitem>

   <listitem>
    <para>Prevent interval from suppressing <literal>:00</literal>
    seconds display</para>
   </listitem>

   <listitem>
    <para>
     New functions <function>pg_get_triggerdef(prettyprint)</function>
     and <function>pg_conversion_is_visible()</function> (Christopher)
    </para>
   </listitem>

   <listitem>
    <para>Allow time to be specified as <literal>040506</> or <literal>0405</> (Tom)</para>
   </listitem>

   <listitem>
    <para>
     Input date order must now be <literal>YYYY-MM-DD</literal> (with 4-digit year) or
     match <varname>datestyle</varname>
    </para>
   </listitem>

   <listitem>
    <para>
     Make <function>pg_get_constraintdef</function> support
     unique, primary-key, and check constraints (Christopher)
    </para>
   </listitem>
  </itemizedlist>
 </sect3>

 <sect3>
  <title>Server-Side Language Changes</title>

  <itemizedlist>
   <listitem>
    <para>
     Prevent PL/pgSQL crash when <literal>RETURN NEXT</literal> is
     used on a zero-row record variable (Tom)
    </para>
   </listitem>

   <listitem>
    <para>
     Make PL/Python's <function>spi_execute</function> interface
     handle null values properly (Andrew Bosma)
    </para>
   </listitem>

   <listitem>
    <para>Allow PL/pgSQL to declare variables of composite types without <literal>%ROWTYPE</literal> (Tom)</para>
   </listitem>

   <listitem>
    <para>Fix PL/Python's <function>_quote()</function> function to handle big integers</para>
   </listitem>

   <listitem>
    <para>Make PL/Python an untrusted language, now called <literal>plpythonu</literal> (Kevin Jacobs, Tom)</para>
    <para>
     The Python language no longer supports a restricted execution
     environment, so the trusted version of PL/Python was removed. If
     this situation changes, a version of PL/Python that can be used
     by non-superusers will be readded.
    </para>
   </listitem>

   <listitem>
    <para>Allow polymorphic PL/pgSQL functions (Joe, Tom)</para>
   </listitem>

   <listitem>
    <para>Allow polymorphic SQL functions (Joe)</para>
   </listitem>

   <listitem>
    <para>
     Improved compiled function caching mechanism in PL/pgSQL with
     full support for polymorphism (Joe)
    </para>
   </listitem>

   <listitem>
    <para>
     Add new parameter <literal>$0</> in PL/pgSQL representing the
     function's actual return type (Joe)
    </para>
   </listitem>

   <listitem>
    <para>
     Allow PL/Tcl and PL/Python to use the same trigger on multiple tables (Tom)
    </para>
   </listitem>

   <listitem>
    <para>
     Fixed PL/Tcl's <function>spi_prepare</function> to accept fully
     qualified type names in the parameter type list
     (Jan)
    </para>
   </listitem>
  </itemizedlist>
 </sect3>

 <sect3>
  <title>psql Changes</title>

  <itemizedlist>
   <listitem>
    <para>Add <literal>\pset pager always</literal> to always use pager (Greg)</para>
    <para>
     This forces the pager to be used even if the number of rows is
     less than the screen height.  This is valuable for rows that
     wrap across several screen rows.
    </para>
   </listitem>

   <listitem><para>Improve tab completion (Rod, Ross Reedstrom, Ian Barwick)</para></listitem>
   <listitem><para>Reorder <literal>\?</> help into groupings (Harald Armin Massa, Bruce)</para></listitem>
   <listitem><para>Add backslash commands for listing schemas, casts, and conversions (Christopher)</para></listitem>

   <listitem>
    <para>
     <command>\encoding</> now changes based on the server parameter
     <varname>client_encoding</varname> (Tom)
    </para>
    <para>
     In previous versions, <command>\encoding</command> was not aware
     of encoding changes made using <literal>SET
     client_encoding</literal>.
    </para>
   </listitem>

   <listitem>
    <para>Save editor buffer into readline history (Ross)</para>
    <para>
     When <command>\e</> is used to edit a query, the result is saved
     in the readline history for retrieval using the up arrow.
    </para>
   </listitem>

   <listitem><para>Improve <command>\d</command> display (Christopher)</para></listitem>
   <listitem><para>Enhance HTML mode to be more standards-conforming (Greg)</para></listitem>

   <listitem>
    <para>New <command>\set AUTOCOMMIT off</command> capability (Tom)</para>
    <para>
     This takes the place of the removed server parameter <varname>autocommit</varname>.
    </para>
   </listitem>

   <listitem>
    <para>New <command>\set VERBOSITY</command> to control error detail (Tom)</para>
    <para>
     This controls the new error reporting details.
    </para>
   </listitem>

   <listitem><para>New prompt escape sequence <literal>%x</literal> to show transaction status (Tom)</para></listitem>
   <listitem><para>Long options for <application>psql</application> are now available on all platforms</para></listitem>
  </itemizedlist>
 </sect3>

 <sect3>
  <title>pg_dump Changes</title>

  <itemizedlist>
   <listitem><para>Multiple pg_dump fixes, including tar format and large objects</para></listitem>
   <listitem><para>Allow pg_dump to dump specific schemas (Neil)</para></listitem>

   <listitem>
    <para>Make pg_dump preserve column storage characteristics (Christopher)</para>
    <para>
     This preserves <literal>ALTER TABLE ... SET STORAGE</literal> information.
    </para>
   </listitem>

   <listitem><para>Make pg_dump preserve <command>CLUSTER</command> characteristics (Christopher)</para></listitem>

   <listitem>
    <para>
     Have pg_dumpall use <command>GRANT</>/<command>REVOKE</> to dump database-level privileges (Tom)
    </para>
   </listitem>

   <listitem>
    <para>
     Allow pg_dumpall to support the options <option>-a</>,
     <option>-s</>, <option>-x</> of pg_dump (Tom)
    </para>
   </listitem>

   <listitem><para>Prevent pg_dump from lowercasing identifiers specified on the command line (Tom)</para></listitem>

   <listitem>
    <para>
     pg_dump options <option>--use-set-session-authorization</option>
     and <option>--no-reconnect</option> now do nothing, all dumps
     use <command>SET SESSION AUTHORIZATION</command>
    </para>
    <para>
     pg_dump no longer reconnects to switch users, but instead always
     uses <command>SET SESSION AUTHORIZATION</command>. This will
     reduce password prompting during restores.
    </para>
   </listitem>

   <listitem>
    <para>Long options for <application>pg_dump</application> are now available on all platforms</para>
    <para>
     <productname>PostgreSQL</productname> now includes its own
     long-option processing routines.
    </para>
   </listitem>
  </itemizedlist>
 </sect3>

 <sect3>
  <title>libpq Changes</title>

  <itemizedlist>
   <listitem>
    <para>
     Add function <function>PQfreemem</function> for freeing memory on
     Windows, suggested for <command>NOTIFY</command> (Bruce)
    </para>
    <para>
     Windows requires that memory allocated in a library be freed by
     a function in the same library, hence
     <function>free()</function> doesn't work for freeing memory
     allocated by libpq. <function>PQfreemem</function> is the proper
     way to free libpq memory, especially on Windows, and is
     recommended for other platforms as well.
    </para>
   </listitem>

   <listitem>
    <para>Document service capability, and add sample file (Bruce)</para>
    <para>
     This allows clients to look up connection information in a
     central file on the client machine.
    </para>
   </listitem>

   <listitem>
    <para>
     Make <function>PQsetdbLogin</function> have the same defaults as
     <function>PQconnectdb</function> (Tom)
    </para>
   </listitem>

   <listitem><para>Allow libpq to cleanly fail when result sets are too large (Tom)</para></listitem>

   <listitem>
    <para>
     Improve performance of function <function>PQunescapeBytea</function> (Ben Lamb)
    </para>
   </listitem>

   <listitem>
    <para>
     Allow thread-safe libpq with <filename>configure</filename>
     option <option>--enable-thread-safety</option> (Lee Kindness,
     Philip Yarra)
    </para>
   </listitem>

   <listitem>
    <para>
     Allow function <function>pqInternalNotice</function> to accept a
     format string and arguments instead of just a preformatted
     message (Tom, Sean Chittenden)
    </para>
   </listitem>

   <listitem>
    <para>
     Control SSL negotiation with <literal>sslmode</literal> values
     <literal>disable</literal>, <literal>allow</literal>,
     <literal>prefer</literal>, and <literal>require</literal> (Jon
     Jensen)
    </para>
   </listitem>

   <listitem>
    <para>Allow new error codes and levels of text (Tom)</para>
   </listitem>

   <listitem>
    <para>Allow access to the underlying table and column of a query result (Tom)</para>
    <para>
     This is helpful for query-builder applications that want to know
     the underlying table and column names associated with a specific
     result set.
    </para>
   </listitem>

   <listitem><para>Allow access to the current transaction status (Tom)</para></listitem>
   <listitem><para>Add ability to pass binary data directly to the server (Tom)</para></listitem>

   <listitem>
    <para>
     Add function <function>PQexecPrepared</function> and
     <function>PQsendQueryPrepared</function> functions which perform
     bind/execute of previously prepared statements (Tom)
     </para>
    </listitem>
  </itemizedlist>
 </sect3>

 <sect3>
  <title>JDBC Changes</title>

  <itemizedlist>
   <listitem><para>Allow <function>setNull</function> on updateable result sets</para></listitem>
   <listitem><para>Allow <function>executeBatch</function> on a prepared statement (Barry)</para></listitem>
   <listitem><para>Support SSL connections (Barry)</para></listitem>
   <listitem><para>Handle schema names in result sets (Paul Sorenson)</para></listitem>
   <listitem><para>Add refcursor support (Nic Ferrier)</para></listitem>
  </itemizedlist>
 </sect3>

 <sect3>
  <title>Miscellaneous Interface Changes</title>

  <itemizedlist>
   <listitem>
    <para>Prevent possible memory leak or core dump during libpgtcl shutdown (Tom)</para>
   </listitem>
   <listitem>
    <para>Add Informix compatibility to ECPG (Michael)</para>
    <para>
     This allows ECPG to process embedded C programs that were
     written using certain Informix extensions.
    </para>
   </listitem>

   <listitem>
    <para>Add type <type>decimal</type> to ECPG that is fixed length, for Informix (Michael)</para>
   </listitem>

   <listitem>
    <para>
     Allow thread-safe embedded SQL programs with
     <filename>configure</filename> option
     <option>--enable-thread-safety</option> (Lee Kindness, Bruce)
    </para>
    <para>
     This allows multiple threads to access the database at the same
     time.
    </para>
   </listitem>

   <listitem>
    <para>Moved Python client PyGreSQL to <ulink url="http://www.pygresql.org"></ulink> (Marc)</para>
   </listitem>
  </itemizedlist>
 </sect3>

 <sect3>
  <title>Source Code Changes</title>

  <itemizedlist>
   <listitem><para>Prevent need for separate platform geometry regression result files (Tom)</para></listitem>
   <listitem><para>Improved PPC locking primitive (Reinhard Max)</para></listitem>
   <listitem><para>New function <function>palloc0</function> to allocate and clear memory (Bruce)</para></listitem>
   <listitem><para>Fix locking code for s390x CPU (64-bit) (Tom)</para></listitem>
   <listitem><para>Allow OpenBSD to use local ident credentials (William Ahern)</para></listitem>
   <listitem><para>Make query plan trees read-only to executor (Tom)</para></listitem>
   <listitem><para>Add macOS startup scripts (David Wheeler)</para></listitem>
   <listitem><para>Allow libpq to compile with Borland C++ compiler (Lester Godwin, Karl Waclawek)</para></listitem>
   <listitem><para>Use our own version of <function>getopt_long()</function> if needed (Peter)</para></listitem>
   <listitem><para>Convert administration scripts to C (Peter)</para></listitem>
   <listitem><para> Bison &gt;= 1.85 is now required to build the <productname>PostgreSQL</> grammar, if building from CVS</para></listitem>
   <listitem><para>Merge documentation into one book (Peter)</para></listitem>
   <listitem><para>Add Windows compatibility functions (Bruce)</para></listitem>
   <listitem><para>Allow client interfaces to compile under MinGW (Bruce)</para></listitem>
   <listitem><para>New <function>ereport()</function> function for error reporting (Tom)</para></listitem>
   <listitem><para>Support Intel compiler on Linux (Peter)</para></listitem>
   <listitem><para>Improve Linux startup scripts (Slawomir Sudnik, Darko Prenosil)</para></listitem>
   <listitem><para>Add support for AMD Opteron and Itanium (Jeffrey W. Baker, Bruce)</para></listitem>
   <listitem>
    <para>Remove <option>--enable-recode</option> option from <command>configure</command></para>
    <para>
     This was no longer needed now that we have <command>CREATE CONVERSION</command>.
    </para>
   </listitem>
   <listitem>
    <para>Generate a compile error if spinlock code is not found (Bruce)</para>
    <para>
     Platforms without spinlock code will now fail to compile, rather
     than silently using semaphores. This failure can be disabled
     with a new <command>configure</command> option.
    </para>
   </listitem>
  </itemizedlist>
 </sect3>

 <sect3>
  <title>Contrib Changes</title>

  <itemizedlist>
   <listitem><para>Change dbmirror license to BSD</para></listitem>
   <listitem><para>Improve earthdistance (Bruno Wolff III)</para></listitem>
   <listitem><para>Portability improvements to pgcrypto (Marko Kreen)</para></listitem>
   <listitem><para>Prevent crash in xml (John Gray, Michael Richards)</para></listitem>
   <listitem><para>Update oracle</para></listitem>
   <listitem><para>Update mysql</para></listitem>
   <listitem><para>Update cube (Bruno Wolff III)</para></listitem>
   <listitem><para>Update earthdistance to use cube (Bruno Wolff III)</para></listitem>
   <listitem><para>Update btree_gist (Oleg)</para></listitem>
   <listitem><para>New tsearch2 full-text search module (Oleg, Teodor)</para></listitem>
   <listitem><para>Add hash-based crosstab function to tablefuncs (Joe)</para></listitem>
   <listitem><para>Add serial column to order <function>connectby()</> siblings in tablefuncs (Nabil Sayegh,Joe)</para></listitem>
   <listitem><para>Add named persistent connections to dblink (Shridhar Daithanka)</para></listitem>
   <listitem><para>New pg_autovacuum allows automatic <command>VACUUM</command> (Matthew T. O'Connor)</para></listitem>
   <listitem><para>Make pgbench honor environment variables <envar>PGHOST</>, <envar>PGPORT</>, <envar>PGUSER</> (Tatsuo)</para></listitem>
   <listitem><para>Improve intarray (Teodor Sigaev)</para></listitem>
   <listitem><para>Improve pgstattuple (Rod)</para></listitem>
   <listitem><para>Fix bug in <function>metaphone()</function> in fuzzystrmatch</para></listitem>
   <listitem><para>Improve adddepend (Rod)</para></listitem>
   <listitem><para>Update spi/timetravel (B&ouml;jthe Zolt&aacute;n)</para></listitem>
   <listitem><para>Fix dbase <option>-s</> option and improve non-ASCII handling (Thomas Behr, M&aacute;rcio Smiderle)</para></listitem>
   <listitem><para>Remove array module because features now included by default (Joe)</para></listitem>
  </itemizedlist>
 </sect3>
 </sect2>
</sect1>
