<!-- doc/src/sgml/release-9.1.sgml -->

<!-- This is (hopefully) up-to-date with commits through 2011-03-08 -->

<sect1 id="release-9-1-alpha">
  <title>Release 9.1alpha4</title>
  <sect2>
    <title>Overview</title>
    <para>
      PostgreSQL alpha releases are snapshots of development code. They
      are intended to preview and test upcoming features and to provide
      the possibility for early feedback. They should not be used in
      production installations or active development projects. While the
      PostgreSQL code is continuously subject to a number of automated
      and manual tests, alpha releases might have serious bugs. Also
      features may be changed incompatibly or removed at any time during
      the development cycle.
    </para>
    <para>
      The development cycle of a PostgreSQL major release alternates
      between periods of development and periods of integration work,
      called commit fests, normally one month each. Alpha releases are
      planned to be produced at the end of every commit fest, thus every
      two months. Since the first commit fest starts within a month from
      the beginning of development altogether, early alpha releases are
      not indicative of the likely feature set of the final release.
    </para>
    <para>
      The release notes below highlight user visible changes and new
      features. There are normally numerous bug fixes and performance
      improvements in every new snapshot of PostgreSQL, and it would be
      too bulky to attempt to list them all. Note that many bug fixes are
      also backported to stable releases of PostgreSQL, and you should be
      using those if you are looking for bug-fix-only upgrades for your
      current installations.
    </para>
    <para>
      These notes are cumulative over all alpha releases of the current
      development cycle.  Items that are new in the latest alpha release are
      <emphasis>emphasized</emphasis>.
    </para>
  </sect2>
  <sect2>
    <title>Migration</title>
    <para>
      To upgrade from any release to an alpha release or from an alpha
      release to any other release will most likely require a
      dump/restore upgrade procedure. It may happen that this is not
      necessary in particular cases, but that is not verified beforehand.
      (The server will warn you in any case when a dump/restore is
      necessary if you attempt to use it with an old data directory.)
      Note, however, that the dump/restore upgrade procedure is expected
      to work for alpha releases, and problems in this area should be
      reported.
    </para>
  </sect2>
  <sect2>
    <title>Testing</title>
    <para>
      The primary reason we release alphas is to get users to test new
      features as early as possible.  If you are interested in helping
      with organized testing, please see
      <ulink url="http://wiki.postgresql.org/wiki/HowToBetaTest">the
      testing information page</ulink>.
      </para>
  </sect2>
  <sect2>
    <title>Changes</title>

    <sect3>
      <title>Replication and Recovery</title>
      <itemizedlist>

       <listitem>
        <para>
         <emphasis>Support named restore points</emphasis>
        </para>
        <para>
         Named restore points can be created using a new server function,
         pg_create_restore_point.  A new recovery.conf parameter,
         recovery_target_name, allows recovery to stop at a named restore
         point.
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Add new recovery.conf parameter, pause_at_recovery_target,
         which defaults to on</emphasis>
        </para>
        <para>
         This is a behavior change from previous releases, which entered normal
         running upon reaching the recovery target.
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Add pg_is_xlog_replay_paused, pg_xlog_replay_pause, and
         pg_xlog_replay_resume functions</emphasis>
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Allow standby servers to send information on running
         transactions back to the master</emphasis>
        </para>
        <para>
         When enabled, this prevents most recovery conflicts on the slave,
         but may cause MVCC bloat on the master.
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Support streaming base backups</emphasis>
        </para>
        <para>
         A new client, pg_basebackup, can be used to perform a streaming base
         backup.
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Synchronous replication</emphasis>
        </para>
        <para>
         When enabled, transaction commit will wait for WAL records to be
         replicated before informing the client that a transaction has
         successfully committed.
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>When recovery_target_timeline='latest', periodically
         rescan the archive for new timelines</emphasis>
        </para>
       </listitem>

      </itemizedlist>
    </sect3>

    <sect3>
      <title>SQL Features</title>
      <itemizedlist>

       <listitem>
        <para>
         Add ALTER ... SET SCHEMA support for conversions,
         operators, operator classes, operator families, text search
         configurations, text search dictionaries, text search
         parsers, and text search templates
        </para>
       </listitem>

       <listitem>
        <para>
         Make TRUNCATE ... RESTART IDENTITY restart sequences transactionally
        </para>

        <para>
         Previously, the sequence restart did not roll back on error.
         This meant that an error between truncating and committing
         left the sequences out of sync with the table contents, with
         potentially bad consequences as were noted in a Warning on
         the TRUNCATE man page.
        </para>
       </listitem>

       <listitem>
        <para>
         Prevent invoking I/O conversion casts via
         functional/attribute notation
        </para>
        <para>
         This was found to be confusing in some cases.  The
         functionality is still available via cast syntax.
        </para>
       </listitem>

       <listitem>
        <para>
         Add ALTER TYPE ... ADD/DROP/ALTER/RENAME ATTRIBUTE
        </para>
       </listitem>

       <listitem>
        <para>
         Support triggers on views
        </para>

        <para>
         This adds the SQL-standard concept of an INSTEAD OF trigger,
         which is fired instead of performing a physical
         insert/update/delete.  The trigger function is passed the
         entire old and/or new rows of the view, and must figure out
         what to do to the underlying tables to implement the update.
         So this feature can be used to implement updatable views
         using trigger programming style rather than rule hacking.
         </para>
       </listitem>

       <listitem>
        <para>
         Allow WITH clauses to be attached to INSERT, UPDATE, DELETE
         statements
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Allow INSERT/UPDATE/DELETE to be used inside a WITH
         clause</emphasis>
        </para>
       </listitem>

       <listitem>
        <para>
         Allow new values to be added to an existing enum type
        </para>
       </listitem>

       <listitem>
        <para>
         Recognize functional dependency on primary
         keys
        </para>
        <para>
         This allows a table's other columns to be referenced without listing
         them in GROUP BY, so long as the primary key column(s) are listed in
         GROUP BY.
        </para>
       </listitem>

       <listitem>
        <para>
         Add CREATE TABLE IF NOT EXISTS
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Allow a table's row type to be cast to the table's supertype
         if it's a type table</emphasis>
        </para>
        <para>
         This is analagous to the existing facility that allows casting a row
         type to a supertable's row type.
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Make foreign data wrappers functional, and support FOREIGN
         TABLEs</emphasis>
        </para>
        <para>
         Foreign tables are component of SQL/MED, and provide a framework to
         allow data stored outside the database to be accessed via SQL.
         contrib/file_fdw is provided as a sample foreign data wrapper.
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Allow a unique or primary key constraint to be created
         using an existing index</emphasis>
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Implement Serializable Snapshot Isolation, in order to
         provide a more robust serializable transaction mode</emphasis>
        </para>
        <para>
         In previous releases, the REPEATABLE READ and SERIALIZABLE isolation
         levels were identical.  The historical behavior of REPEATABLE READ is
         unchanged in this release, but SERIALIZABLE now provides stronger
         guarantees.
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Allow foreign key constraints to be added as initially
         NOT VALID, and validated later</emphasis>
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Allow multiple collations to be used within a single
         database</emphasis>
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Support extensions, which provide a cleaner method for
         installing and upgrading add-on modules, such as those in contrib
         </emphasis>
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Teach ALTER TABLE ... SET DATA TYPE to avoid a table write
         in some cases where it isn't necessary
         </emphasis>
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Add ENCODING option to COPY TO/FROM</emphasis>
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Allow binary I/O of type "void"</emphasis>
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Rearrange snapshot handlling to make rule expansion more
         consistent</emphasis>
        </para>
        <para>
         Portals, SQL functions, and SPI all now agree that a completely new
         MVCC snapshot should be obtained only after fully executing each
         original query.  This is equivalent to the prior behavior of EXPLAIN
         ANALYZE.  It eliminates one source of concurrency hazards for
         rules, and should also be marginally faster.
        </para>
       </listitem>

      </itemizedlist>
    </sect3>
    <sect3>
      <title>Performance</title>
      <itemizedlist>

       <listitem>
        <para>
         Optimize the commit_siblings configuration parameter
        </para>
       </listitem>

       <listitem>
        <para>
         KNN GiST, otherwise known as order-by-operator support for GiST
        </para>

        <para>
         This can be used to optimize nearest-neighbor searches.
        </para>
       </listitem>

       <listitem>
        <para>
         Improve process shutdown speed
        </para>
       </listitem>

       <listitem>
        <para>
         Speed up conversion of signed integers to C strings
        </para>
       </listitem>

       <listitem>
        <para>
         Support MergeAppend plans, to allow sorted output
         from append relations
        </para>

        <para>
         This eliminates the former need to sort the output of an
         Append scan when an ordered scan of an inheritance tree is
         wanted.  This should be particularly useful for fast-start
         cases such as queries with LIMIT.
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Support unlogged tables</emphasis>
        </para>
        <para>
         The contents of an unlogged table are not WAL-logged; thus, they
         are not replicated and are truncated whenever the database system
         enters recovery.  Indexes on unlogged tables are also unlogged, but
         GIST indexes on unlogged tables are not currently supported.
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Hash joins now support right and full outer joins</emphasis>
        </para>
        <para>
         Previously, full joins could be implemented only as a merge join,
         and left and right outer joins could only hash the table on the
         nullable side of the join.  This optimization is particularly
         advantageous when the non-nullable side of a left or right outer
         join is much smaller than the nullable side.
        </para>
       </listitem>

       <listitem>
        <para>
         Reduce the memory requirement for large ispell dictionaries
        </para>
       </listitem>

       <listitem>
        <para>
         Teach CLUSTER to use seqscan-and-sort when it's faster than
         indexscan
        </para>
       </listitem>

       <listitem>
        <para>
         Improve GIN indexscan cost estimation
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Fix GIN to support null keys, empty and null items, and
         full index scans</emphasis>
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Teach GIN to combine duplicate keys even across different
         quals</emphasis>
        </para>
       </listitem>

       <listitem>
        <para>
         Performance improvements in pg_upgrade for uses with many tables
        </para>
       </listitem>

       <listitem>
        <para>
         Reduce lock levels of CREATE TRIGGER and some ALTER
         TABLE, CREATE RULE actions
        </para>
       </listitem>

       <listitem>
        <para>
         Add some knowledge about prefix matches to
         tsmatchsel()
        </para>
       </listitem>

       <listitem>
        <para>
         Replace the naive HYPOT() macro with a
         standards-conformant hypotenuse function
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Avoid unnecessary detoast when comparing unequal-length text
         or bytea values for equality or inequality</emphasis>
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Try to compact the background writer's fsync queue when
         it overflows, instead of doing an fsync per block written</emphasis>
        </para>
       </listitem>

      </itemizedlist>
    </sect3>
    <sect3>
      <title>Server Settings</title>
      <itemizedlist>

       <listitem>
        <para>
         Change the default value of
         <literal>standard_conforming_strings</> to
         <literal>on</>
        </para>
        <warning>
         <para>
          This is a significant incompatibility with previous releases,
          because it may break unwary applications in security-critical ways.
         </para>
        </warning>
       </listitem>

       <listitem>
        <para>
         Add <literal>log_file_mode</> parameter
        </para>
        <para>
         This allows control of the file permissions set on log files created
         by the syslogger process.
        </para>
       </listitem>

       <listitem>
        <para>
         Add <literal>restart_after_crash</> parameter
        </para>
        <para>
         Normally, we automatically restart after a backend crash, but in
         some cases when PostgreSQL is invoked by clusterware it may be
         desirable to suppress this behavior, so we now provide an option which
         does that.
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Teach replication connections to respect the value of
         log_connections</emphasis>
        </para>
        <para>
         Previously, they were always logged.
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Log restartpoints in the same fashion as
         checkpoints</emphasis>
        </para>
        <para>
         Previously, less information was logged for restartpoints.
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>By default, set wal_buffers to a reasonable value, based
         on the setting for shared_buffers</emphasis>
        </para>
       </listitem>

      </itemizedlist>
    </sect3>
    <sect3>
      <title>Administration and Monitoring</title>
      <itemizedlist>

       <listitem>
        <para>
         Instrument checkpoint sync calls
        </para>
       </listitem>

       <listitem>
        <para>
         Use the same lexer for recovery.conf that has been used for postgresql.conf
        </para>

        <para>
         Among other things, this allows values in recovery.conf to be unquoted.
        </para>
       </listitem>

       <listitem>
        <para>
         Add column buffers_backend_fsync to pg_stat_bgwriter
        </para>
       </listitem>

       <listitem>
        <para>
         Add monitoring function pg_last_xact_replay_timestamp()
        </para>
       </listitem>

       <listitem>
        <para>
         Allow pg_ctl to register the service in either AUTO or DEMAND start
         type
        </para>
       </listitem>

       <listitem>
        <para>
         Support host names and host key word <literal>all</literal>
         in <filename>pg_hba.conf</filename>
        </para>
       </listitem>

       <listitem>
        <para>
         Make EXPLAIN show the function call expression of a
         FunctionScan plan node, but only in VERBOSE mode
        </para>
       </listitem>

       <listitem>
        <para>
         Make EXPLAIN print PARAM_EXEC Params as
         the referenced expressions, rather than just $N
        </para>
       </listitem>

       <listitem>
        <para>
         Add vacuum and analyze counters to pg_stat_*_tables
         views
        </para>
       </listitem>

       <listitem>
        <para>
         Add stats functions and views to provide access to a
         transaction's own statistics counts
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Implement remaining fields of
         information_schema.sequences view</emphasis>
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Add a "conflicts" column to pg_stat_database</emphasis>
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>New system view pg_stat_database_conflicts</emphasis>
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>New system view pg_stat_replication</emphasis>
        </para>
        <para>
         This view shows which replication slaves are connected to the master,
         and reports their status and replication progress.
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>When an autovacuum worker (other than one performing an
         anti-wraparound vacuum) is unable to obtain a lock on the target
         relation without blocking, skip the relation</emphasis>
        </para>
        <para>
         This avoids pinning down an autovacuum worker.  The next autovacuum
         cycle will try again. 
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Track time of last statistics reset on databases and
         bgwriter</emphasis>
        </para>
       </listitem>

      </itemizedlist>
    </sect3>
    <sect3>
      <title>Security</title>
      <itemizedlist>

       <listitem>
        <para>
         Add SECURITY LABEL command
        </para>
        <para>
         This is intended as infrastructure to support integration
         with label-based mandatory access control systems such as
         SE-Linux.
        </para>
       </listitem>

       <listitem>
        <para>
         Add server authentication over Unix-domain
         sockets
        </para>
        <para>
         This adds a libpq connection parameter <literal>requirepeer</> that
         specifies the user name that the server process is expected to run
         under.
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Add REPLICATION privilege for ROLEs</emphasis>
        </para>
        <para>
         This makes it possible for replication to be performed by a
         non-superuser account.
        </para>
       </listitem>

      </itemizedlist>
    </sect3>
    <sect3>
      <title>Built-in Functions</title>
      <itemizedlist>

       <listitem>
        <para>
         Add pg_read_binary_file() and whole-file-at-once
         versions of pg_read_file()
        </para>
       </listitem>

       <listitem>
        <para>
         Add new function format(), for sprintf-like string formatting
        </para>
       </listitem>

       <listitem>
        <para>
         Add pg_describe_object() function to obtain textual
         descriptions of objects as stored in pg_depend
        </para>
       </listitem>

       <listitem>
        <para>
         Accept <literal>public</literal> as a pseudo-role
         name in <literal>has_table_privilege()</literal> and friends
         to see if a particular privilege has been granted to
         <literal>PUBLIC</literal>
        </para>
       </listitem>

       <listitem>
        <para>
         Add string functions: concat(), concat_ws(), left(),
         right(), and reverse()
        </para>
       </listitem>

       <listitem>
        <para>
         Add three-parameter forms of array_to_string and
         string_to_array
        </para>
       </listitem>

       <listitem>
        <para>
         Add XMLEXISTS function
        </para>
       </listitem>

       <listitem>
        <para>
         Add xpath_exists() function
        </para>
        <para>
         This is equivalent to XMLEXISTS except that it offers support for
         namespace mapping.
        </para>
       </listitem>

       <listitem>
        <para>
         Add xml_is_well_formed, xml_is_well_formed_document,
         xml_is_well_formed_content functions to the core XML
         code
        </para>
        <para>
         These supersede a version previously offered by contrib/xml2.
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Change pg_last_xlog_receive_location not to move
         backwards</emphasis>
        </para>
       </listitem>

      </itemizedlist>
    </sect3>
    <sect3>
      <title>Data Types</title>
      <itemizedlist>

       <listitem>
        <para>
         Allow numeric to use a more compact, 2-byte header in
         many cases
        </para>
       </listitem>

       <listitem>
        <para>
         Add support for dividing money by money (yielding a
         float8 result) and for casting between money and numeric
        </para>
       </listitem>

      </itemizedlist>
    </sect3>
    <sect3>
      <title>Server Tools</title>
      <itemizedlist>

       <listitem>
        <para>
         Add options to force quoting of all
         identifiers
        </para>
        <para>
         This includes a quote_all_identifiers parameter which affects the
         behavior of the backend, and a --quote-all-identifiers argument to
         pg_dump and pg_dumpall which sets the parameter and also affects the
         quoting done internally by those applications.
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Add a directory output format to pg_dump</emphasis>
        </para>
       </listitem>

      </itemizedlist>
    </sect3>
    <sect3>
      <title>psql</title>
      <itemizedlist>

       <listitem>
        <para>
         Add <quote>S</quote> option to \dn command in psql
        </para>
        <para>
         System schemas are now hidden by default by \dn.
        </para>
       </listitem>

       <listitem>
        <para>
         Add \conninfo command to psql, to show current connection
         info
        </para>
       </listitem>

       <listitem>
        <para>
         Extend psql's \e and \ef commands so that a line number
         can be specified, and the editor's cursor will be initially placed
         on that line
        </para>
        <para>
         To avoid assumptions about what switch the user's editor takes for
         this purpose, there is a new psql variable EDITOR_LINENUMBER_SWITCH
         with (at present) no default value.
        </para>
       </listitem>
       <listitem>
        <para>
         Add a \sf (show function) command to psql, for those
         times when you need to look at a function but don't wish to fire up
         an editor
        </para>
       </listitem>

       <listitem>
        <para>
         Make psql distinguish between unique indices and unique
         constraints in \d printout
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Add a \dL command to psql, to list procedural
         languages</emphasis>
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Allow psql to automatically deduce the client encoding from
         the locale</emphasis>
        </para>
       </listitem>

      </itemizedlist>
    </sect3>
    <sect3>
      <title>libpq</title>
      <itemizedlist>

       <listitem>
        <para>
         Add PQlibVersion() function
        </para>
       </listitem>

       <listitem>
        <para>
         When reporting the server as not responding, if the
         hostname was supplied, also print the IP address
        </para>
        <para>
         This allows IPv4 and IPv6 failures to be distinguished.  Also
         useful when a hostname resolves to multiple IP addresses.
        </para>
       </listitem>

       <listitem>
        <para>
         Add functions PQping and PQpingParams to allow
         detection of the server's status, including a status where
         the server is running but refuses ordinary connections
        </para>
        <para>
         pg_ctl uses the new function.  This fixes the case where
         pg_ctl reports that the server is not running (cannot
         connect) but in fact it is running.
        </para>
       </listitem>

      </itemizedlist>
    </sect3>
    <sect3>
      <title>ecpg</title>
      <itemizedlist>
       <listitem>
        <para>
         <emphasis>Allow ecpg to accept dynamic cursor names even in WHERE
         CURRENT OF clauses</emphasis>
        </para>
       </listitem>
      </itemizedlist>
    </sect3>
    <sect3>
      <title>Procedural Languages</title>
      <sect4>
       <title>PL/pgSQL</title>
      <itemizedlist>

       <listitem>
        <para>
         Modify the handling of RAISE without parameters so that
         the error it throws can be caught in the same places that could
         catch an ordinary RAISE ERROR in the same location
        </para>
        <para>
         The previous coding insisted on throwing the error from the block
         containing the active exception handler; which is arguably more
         surprising, and definitely unlike Oracle's behavior.
        </para>
       </listitem>

       <listitem>
        <para>
         Remove ancient PL/pgSQL line numbering hack
        </para>
        <para>
         PL/pgSQL used to count the second line of the function body as
         <quote>line 1</>, if the first line was zero-length.
         While this hack arguably has some benefit in terms of making
         PL/pgsql's line numbering match the programmer's expectations, it
         also makes PL/pgsql inconsistent with the remaining PLs, making it
         difficult for clients to reliably determine where the error
         actually is.  On balance, it seems better to be consistent.
        </para>
       </listitem>

      </itemizedlist>
      </sect4>

      <sect4>
       <title>PL/Perl</title>

       <itemizedlist>
        <listitem>
         <para>
          Allow generic record arguments to PL/Perl functions
         </para>
        </listitem>

        <listitem>
         <para>
          <emphasis>Convert PostgreSQL arrays passed to PL/perl functions to
          Perl arrays</emphasis>
         </para>
        </listitem>
       </itemizedlist>
      </sect4>

      <sect4>
       <title>PL/Python</title>
       <itemizedlist>

        <listitem>
         <para>
          <emphasis>Fix an error when a set-returning function fails halfway
          through</emphasis>
         </para>
        </listitem>

        <listitem>
         <para>
          <emphasis>Make plpy.Fatal() raise FATAL, rather than ERROR</emphasis>
         </para>
        </listitem>

        <listitem>
         <para>
          <emphasis>Skip dropped attributes when converting Python objects to
          tuples</emphasis>
         </para>
        </listitem>

        <listitem>
         <para>
          <emphasis>Improve the handling of exceptions</emphasis>
         </para>
         <para>
          Fix the way that exceptions are handled by the plpy module for Python
          3.  Get rid of the global variable holding the error state, and
          instead arrange to report PostgreSQL errors to Python immediately.
          Call PLy_spi_execute_fetch_result inside the try/catch block, so that
          errors from fetching tuples are correct reported as errors in the
          SPI call.  Use the built-in TypeError, not SPIError, for errors
          having to do with argument counts or types.  Use SPIError, not simply
          plpy.Error, for errors in PLy_spi_execute_plan.  Do not set
          a Python exception if PyArg_ParseTuple failed, as it already sets
          the correct exception.
         </para>
        </listitem>

        <listitem>
         <para>
          <emphasis>Improve error reporting</emphasis>
         </para>
         <para>Better error messages for errors in compiling anonymous
          PL/Python blocks.  Avoid prefixing error messages with the string
          "PL/Python: ", which is redundant, given the error
          context.  Provide a separate exception class for each error code
          the backend defines, and make it possible to get the SQLSTATE from
          the exception object.  Report Python errors from iterators
          using PLy_elog, so that the Python exception is included in the
          exception, and to avoid setting the errcode to
          ERRCODE_DATA_EXCEPTION.
         </para>
        </listitem>

        <listitem>
         <para>
          <emphasis>Check PL/Python functions for syntax errors at creation
          time</emphasis>
         </para>
         <para>
          Previously, even gross syntax errors would not be detected until
          the function was executed.
         </para>
        </listitem>

        <listitem>
         <para>
          <emphasis>Allow Python try/catch blocks to catch exceptions arising
          from SPI calls</emphasis>
         </para>
        </listitem>

        <listitem>
         <para>
          <emphasis>Invalidate PL/python functions with composite type
          arguments when the type changes</emphasis>
         </para>
        </listitem>

        <listitem>
         <para>
          <emphasis>Add quoting functions plpy.quote_ident, plpy.quote_literal,
          and plpy.quote_nullable</emphasis>
         </para>
        </listitem>

        <listitem>
         <para>
          <emphasis>Support table functions</emphasis>
         </para>
        </listitem>

        <listitem>
         <para>
          <emphasis>Add a plpy.subtransaction() context manager</emphasis>
         </para>
        </listitem>

        <listitem>
         <para>
          <emphasis>Assorted code cleanup</emphasis>
         </para>
         <para>
          We now use HTABs instead of Python dictionary objects to cache
          procedures.  palloc is used in TopMemoryContext instead of malloc.
          Avoid use of undocumented API PyObject_NEW.  Free plan values in
          the PlyPlanObject dealloc function.  Add braces around an if block,
          for readability.  Refactor PLy_spi_prepare to save two levels of
          indentation.  Avoid palloc(0).
         </para>
        </listitem>
       </itemizedlist>
      </sect4>
    </sect3>

    <sect3>
      <title>Additional Supplied Modules</title>
      <itemizedlist>

       <listitem>
        <para>
         New module contrib/auth_delay
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>New module contrib/sepgsql, an SE-Linux integration for
         PostgreSQL</emphasis>
        </para>
       </listitem>

       <listitem>
        <para>
         Updates to contrib/isn ISBN tables
        </para>
       </listitem>

       <listitem>
        <para>
         Add the ability to compute per-statement latencies (ie,
         average execution times) to pgbench
        </para>
       </listitem>

       <listitem>
        <para>
         Teach levenshtein() about multi-byte
         characters
        </para>
       </listitem>

       <listitem>
        <para>
         Add btree_gist support for searching on <quote>not
         equals</quote>
        </para>
       </listitem>

       <listitem>
        <para>
         Add ssl_cipher() and ssl_version() functions to
         contrib/sslinfo
        </para>
       </listitem>

       <listitem>
        <para>
         Remove the arbitrary (and undocumented) limit on the
         number of parameter=value pairs that can be handled by
         xslt_process()
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>New module contrib/pg_test_fsync, replacing
         src/tools/test_fsync</emphasis>
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>In contrib/pageinspect, fix the heap_page_item to return
         infomasks as 32 bit values</emphasis>
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>In contrib/btree_gist, support KNN GiST searches</emphasis>
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>In contrib/pg_trgm, support LIKE, ILIKE, and KNN GiST
         searches</emphasis>
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Several improvements to contrib/intarray</emphasis>
        </para>
        <para>
         Correct the behavior of array containment operators, so that an empty
         array is contained in any other array.  Fix bogus failures where
         operators would claim that nulls were present when they really
         weren't.  Remove arbitrary restriction to 1-D arrays.
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Fix pg_upgrade not to insist on pg_dumpall and psql in the
         old cluster, since we don't need them, but do check for pg_resetxlog
         in the old and new clusters, since we do.  Avoid a useless attempt
         to call pg_config in the old cluster.</emphasis>
        </para>
       </listitem>

      </itemizedlist>
    </sect3>
    <sect3>
      <title>Source Code, Build Options</title>
      <itemizedlist>

       <listitem>
        <para>
         Rewrite the GiST insertion logic so that the
         post-recovery cleanup stage to finish incomplete inserts or
         splits is not needed anymore
        </para>
       </listitem>

       <listitem>
        <para>
         Add support for collecting <quote>minidump</quote>-style crash dumps
         on Windows
        </para>
       </listitem>

       <listitem>
        <para>
         Replace pg_class.relistemp column with relpersistence
        </para>

        <para>
         This is for upcoming work on unlogged and global temporary tables.
        </para>
       </listitem>

       <listitem>
        <para>
         GNU make 3.80 or newer is now required
        </para>
       </listitem>

       <listitem>
        <para>
         Improved support for parallel make, make -k, and make -q
        </para>
       </listitem>

       <listitem>
        <para>
         Include the backend ID in the relpath of temporary
         relations
        </para>
        <para>
         This allows us to reliably remove all leftover temporary relation
         files on cluster startup without reference to system catalogs or
         WAL; therefore, we no longer include temporary relations in
         XLOG_XACT_COMMIT and XLOG_XACT_ABORT WAL records.
        </para>
       </listitem>

       <listitem>
        <para>
         Rewrite COMMENT ON <replaceable>object</> code for better
         modularity, and add necessary locking
        </para>
       </listitem>

       <listitem>
        <para>
         Add a hook in ExecCheckRTPerms() for eventual use by
         external security-checking modules
        </para>
       </listitem>

       <listitem>
        <para>
         Standardize names and calling conventions of
         get_whatever_oid functions
        </para>
       </listitem>

       <listitem>
        <para>
         Make NestLoop plan nodes pass outer-relation variables
         into their inner relation using the general PARAM_EXEC executor
         parameter mechanism, rather than the ad-hoc kluge of passing the
         outer tuple down through ExecReScan
        </para>
       </listitem>

       <listitem>
        <para>
         Make details of the Numeric representation private to
         numeric.c
        </para>
       </listitem>

       <listitem>
        <para>
         Suppress some compiler warnings from
         <literal>clang</>
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Allow make check in PL directories</emphasis>
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>Add a make check-world target</emphasis>
        </para>
       </listitem>

       <listitem>
        <para>
         <emphasis>PGXS support for contrib/hstore</emphasis>
        </para>
       </listitem>

      </itemizedlist>
    </sect3>
  </sect2>
</sect1>
