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postgres/doc/src/sgml/ref/release_savepoint.sgml
Peter Eisentraut 3c49c6facb Convert documentation to DocBook XML
Since some preparation work had already been done, the only source
changes left were changing empty-element tags like <xref linkend="foo">
to <xref linkend="foo"/>, and changing the DOCTYPE.

The source files are still named *.sgml, but they are actually XML files
now.  Renaming could be considered later.

In the build system, the intermediate step to convert from SGML to XML
is removed.  Everything is build straight from the source files again.
The OpenSP (or the old SP) package is no longer needed.

The documentation toolchain instructions are updated and are much
simpler now.

Peter Eisentraut, Alexander Lakhin, Jürgen Purtz
2017-11-23 09:44:28 -05:00

131 lines
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<!--
doc/src/sgml/ref/release_savepoint.sgml
PostgreSQL documentation
-->
<refentry id="sql-release-savepoint">
<indexterm zone="sql-release-savepoint">
<primary>RELEASE SAVEPOINT</primary>
</indexterm>
<indexterm zone="sql-release-savepoint">
<primary>savepoints</primary>
<secondary>releasing</secondary>
</indexterm>
<refmeta>
<refentrytitle>RELEASE SAVEPOINT</refentrytitle>
<manvolnum>7</manvolnum>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>RELEASE SAVEPOINT</refname>
<refpurpose>destroy a previously defined savepoint</refpurpose>
</refnamediv>
<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"/>.)
Destroying a savepoint when
it is no longer needed allows 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
an 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 table1 VALUES (3);
SAVEPOINT my_savepoint;
INSERT INTO table1 VALUES (4);
RELEASE SAVEPOINT my_savepoint;
COMMIT;
</programlisting>
The above transaction will insert both 3 and 4.
</para>
</refsect1>
<refsect1>
<title>Compatibility</title>
<para>
This command conforms to the <acronym>SQL</acronym> standard. The standard
specifies that the key word <literal>SAVEPOINT</literal> is
mandatory, but <productname>PostgreSQL</productname> allows it to
be omitted.
</para>
</refsect1>
<refsect1>
<title>See Also</title>
<simplelist type="inline">
<member><xref linkend="sql-begin"/></member>
<member><xref linkend="sql-commit"/></member>
<member><xref linkend="sql-rollback"/></member>
<member><xref linkend="sql-rollback-to"/></member>
<member><xref linkend="sql-savepoint"/></member>
</simplelist>
</refsect1>
</refentry>