release-9.2.sgml

<!-- doc/src/sgml/release-9.2.sgml -->
<!-- See header comment in release.sgml about typical markup -->

 <sect1 id="release-9-2">
  <title>Release 9.2</title>

  <note>
   <title>Release Date</title>
   <simpara>2012-??-??</simpara>
   <simpara>CURRENT AS OF 2012-05-09</simpara>
  </note>

  <sect2>
   <title>Overview</title>

   <para>
    NARRATIVE HERE. Major enhancements include:
   </para>

   <itemizedlist>
    <listitem><para>MAJOR LIST HERE</para></listitem>
    <!-- This list duplicates items below, but without authors or details-->

   </itemizedlist>

   <para>
    The above items are explained in more detail in the sections below.
   </para>

  </sect2>

  <sect2>

  <title>Migration to Version 9.2</title>

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

   <para>
    Version 9.2 contains a number of changes that may affect compatibility
    with previous releases.  Observe the following incompatibilities:
   </para>

   <sect3>
    <title>Functions</title>

    <itemizedlist>

      <listitem>
       <para>
        Ensure that <link
        linkend="functions-xml-processing"><function>xpath()</></link>
        escapes special characters in string values (Florian Pflug)
       </para>

       <para>
        Without this it is possible to output illegal
        <acronym>XML</acronym>.
       </para>
      </listitem>

      <listitem>
       <para>
        Remove <link linkend="hstore">hstore</link>'s <literal>=&gt;</>
        operator (Robert Haas)
       </para>

       <para>
        Users should now use hstore(text, text).  Since
        <productname>PostgreSQL</productname> 9.0, a warning message is
        emitted when an operator named =&gt; is created because
        the <acronym>SQL</acronym> standard reserves that token for
        another use.
       </para>
      </listitem>

      <listitem>
       <para>
        Have <link
        linkend="functions-admin-dbobject"><function>pg_relation_size()</></link>
        and friends return NULL if the object does not exist (Phil Sorber)
       </para>

       <para>
        This prevents queries that call these functions from returning
        errors during concurrent drop operations.
       </para>
      </listitem>

      <listitem>
       <para>
        Remove the <link
        linkend="catalog-pg-tablespace"><structname>spclocation</></link>
        field from <structname>pg_tablespace</> (Magnus Hagander)
       </para>

       <para>
        This field was duplicative of the symbolic links already
        present in the data directory.  This allows tablespace
        directories to be moved while the server is down.  Also add
        <function>pg_tablespace_location()</> to allow querying of the
        symbolic links.
       </para>
      </listitem>

      <listitem>
       <para>
        Move <type>tsvector</> most-common-element statistics to new
        <link linkend="view-pg-stats"><structname>pg_stats</></link> columns
        (Alexander Korotkov)
       </para>

       <para>
        Consult <structname>most_common_elems</>
        and <structname>most_common_elem_freqs</> for the data formerly
        available in <structname>most_common_vals</>
        and <structname>most_common_freqs</>.
       </para>
      </listitem>

    </itemizedlist>

    <sect4>
     <title>Temporal Functions</title>

     <itemizedlist>

      <listitem>
       <para>
        Have <link
        linkend="functions-datetime-extract"><function>EXTRACT</></link> of
        a non-timezone-aware value measure the epoch from local midnight,
        not <acronym>UTC</acronym> midnight (Tom Lane)
       </para>

       <para>
        Having these computations depend on <acronym>UTC</acronym>
        was inconsistent.  The old behavior is available by casting the
        value to timestamp with time zone.
       </para>
      </listitem>

      <listitem>
       <para>
        Properly parse time strings with trailing <literal>yesterday</>,
        <literal>today</>, and <literal>tomorrow</> (Dean Rasheed)
       </para>

       <para>
        Previously, <command>SELECT '04:00:00
        yesterday'::timestamp</command> returned yesterday's date at
        midnight.
       </para>
      </listitem>

      <listitem>
       <para>
        Fix <link
        linkend="functions-formatting"><function>to_date()</></link> and
        <function>to_timestamp()</> to wrap incomplete dates toward 2020
        (Bruce Momjian)
       </para>

       <para>
        Previously, supplied years and year masks of less than four digits
        wrapped inconsistently.
       </para>
      </listitem>

     </itemizedlist>
    </sect4>

   </sect3>

   <sect3>
    <title>Object Modification</title>

    <itemizedlist>

      <listitem>
       <para>
        Prevent  <link linkend="SQL-ALTERDOMAIN"><command>ALTER
        DOMAIN</command></link> from working on non-domain types (Peter
        Eisentraut)
       </para>

       <para>
        Owner and schema changes were previously possible on non-domain
        types.
       </para>
      </listitem>

      <listitem>
       <para>
        No longer auto-lowercase procedural language names (Robert Haas)
       </para>