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Allow optional SAVEPOINT keyword in RELEASE and ROLLBACK TO, for greater

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compliance with SQL2003 spec syntax.

Oliver Jowett
This commit is contained in:
Tom Lane
2004-08-12 19:12:21 +00:00
parent 10249abfa1
commit a583675108
8 changed files with 118 additions and 94 deletions
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doc/src/sgml/ref/release_savepoint.sgml Normal file
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<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/release_savepoint.sgml,v 1.1 2004/08/12 19:12:21 tgl Exp $
PostgreSQL documentation
-->
<refentry id="SQL-RELEASE-SAVEPOINT">
<refmeta>
<refentrytitle id="SQL-RELEASE-SAVEPOINT-TITLE">RELEASE SAVEPOINT</refentrytitle>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>RELEASE SAVEPOINT</refname>
<refpurpose>destroy a previously defined savepoint</refpurpose>
</refnamediv>
<indexterm zone="sql-release-savepoint">
<primary>RELEASE SAVEPOINT</primary>
</indexterm>
<indexterm zone="sql-release-savepoint">
<primary>savepoints</primary>
<secondary>releasing</secondary>
</indexterm>
<refsynopsisdiv>
<synopsis>
RELEASE [ SAVEPOINT ] <replaceable>savepoint_name</replaceable>
</synopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<command>RELEASE SAVEPOINT</command> destroys a savepoint previously defined
in the current transaction.
</para>
<para>
Destroying a savepoint makes it unavailable as a rollback point,
but it has no other user visible behavior. It does not undo the
effects of commands executed after the savepoint was established.
(To do that, see <xref linkend="sql-rollback-to"
endterm="sql-rollback-to-title">.) Destroying a savepoint when
it is no longer needed may allow the system to reclaim some resources
earlier than transaction end.
</para>
<para>
<command>RELEASE SAVEPOINT</command> also destroys all savepoints that were
established after the named savepoint was established.
</para>
</refsect1>
<refsect1>
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><replaceable>savepoint_name</replaceable></term>
<listitem>
<para>
The name of the savepoint to destroy.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Notes</title>
<para>
Specifying a savepoint name that was not previously defined is an error.
</para>
<para>
It is not possible to release a savepoint when the transaction is in
aborted state.
</para>
<para>
If multiple savepoints have the same name, only the one that was most
recently defined is released.
</para>
</refsect1>
<refsect1>
<title>Examples</title>
<para>
To establish and later destroy a savepoint:
<programlisting>
BEGIN;
INSERT INTO table VALUES (3);
SAVEPOINT my_savepoint;
INSERT INTO table VALUES (4);
RELEASE SAVEPOINT my_savepoint;
COMMIT;
</programlisting>
The above transaction will insert both 3 and 4.
</para>
</refsect1>
<refsect1>
<title>Compatibility</title>
<para>
The SQL2003 standard specifies that the keyword SAVEPOINT is mandatory.
<productname>PostgreSQL</productname> allows the SAVEPOINT keyword to be
omitted. Otherwise, this command is fully conforming.
</para>
</refsect1>
<refsect1>
<title>See Also</title>
<simplelist type="inline">
<member><xref linkend="sql-begin" endterm="sql-begin-title"></member>
<member><xref linkend="sql-commit" endterm="sql-commit-title"></member>
<member><xref linkend="sql-rollback" endterm="sql-rollback-title"></member>
<member><xref linkend="sql-rollback-to" endterm="sql-rollback-to-title"></member>
<member><xref linkend="sql-savepoint" endterm="sql-savepoint-title"></member>
</simplelist>
</refsect1>
</refentry>
<!-- Keep this comment at the end of the file
Local variables:
mode: sgml
sgml-omittag:nil
sgml-shorttag:t
sgml-minimize-attributes:nil
sgml-always-quote-attributes:t
sgml-indent-step:1
sgml-indent-data:t
sgml-parent-document:nil
sgml-default-dtd-file:"../reference.ced"
sgml-exposed-tags:nil
sgml-local-catalogs:"/usr/lib/sgml/catalog"
sgml-local-ecat-files:nil
End:
-->