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RESET SESSION, plus related new DDL commands. Patch from Marko Kreen,

Browse Source 
reviewed by Neil Conway. This patch adds the following DDL command
variants: RESET SESSION, RESET TEMP, RESET PLANS, CLOSE ALL, and
DEALLOCATE ALL. RESET SESSION is intended for use by connection
pool software and the like, in order to reset a client session
to something close to its initial state.

Note that while most of these command variants can be executed
inside a transaction block (but are not transaction-aware!),
RESET SESSION cannot. While this is inconsistent, it is intended
to catch programmer mistakes: RESET SESSION in an open transaction
block is probably unintended.
This commit is contained in:
Neil Conway
2007-04-12 06:53:49 +00:00
parent e6e47f278d
commit d13e903bea
25 changed files with 479 additions and 38 deletions
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63
doc/src/sgml/ref/reset.sgml
View File

@@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/reset.sgml,v 1.32 2006/09/16 00:30:19 momjian Exp $
$PostgreSQL: pgsql/doc/src/sgml/ref/reset.sgml,v 1.33 2007/04/12 06:53:46 neilc Exp $
PostgreSQL documentation
-->
@@ -22,9 +22,10 @@ PostgreSQL documentation
<synopsis>
RESET <replaceable class="PARAMETER">configuration_parameter</replaceable>
RESET ALL
RESET { PLANS | SESSION | TEMP | TEMPORARY }
</synopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
@@ -41,7 +42,7 @@ SET <replaceable class="parameter">configuration_parameter</replaceable> TO DEFA
<para>
The default value is defined as the value that the parameter would
have had, had no <command>SET</> ever been issued for it in the
have had, if no <command>SET</> ever been issued for it in the
current session. The actual source of this value might be a
compiled-in default, the configuration file, command-line options,
or per-database or per-user default settings. See <xref
@@ -52,6 +53,15 @@ SET <replaceable class="parameter">configuration_parameter</replaceable> TO DEFA
See the <command>SET</> reference page for details on the
transaction behavior of <command>RESET</>.
</para>
<para>
<command>RESET</> can also be used to release internal resources
that are usually released at the end of session. <command>RESET
TEMP</> drops all temporary tables created in the current session.
<command>RESET PLANS</> releases all internally cached plans.
<command>RESET SESSION</> releases all externally visible temporary
resources associated with the current session.
</para>
</refsect1>
<refsect1>
@@ -76,9 +86,56 @@ SET <replaceable class="parameter">configuration_parameter</replaceable> TO DEFA
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>TEMP, TEMPORARY</literal></term>
<listitem>
<para>
Drops all temporary tables created in the current session.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>PLANS</literal></term>
<listitem>
<para>
Releases all cached query plans.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>SESSION</literal></term>
<listitem>
<para>
Releases all temporary resources associated with the current
session. This has the same effect as executing the following
command sequence:
<synopsis>
SET SESSION AUTHORIZATION DEFAULT;
RESET ALL;
DEALLOCATE ALL;
CLOSE ALL;
UNLISTEN *;
RESET PLANS;
RESET TEMP;
</synopsis>
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Notes</title>
<para>
<command>RESET SESSION</> cannot be executed inside a transaction block.
</para>
</refsect1>
<refsect1>
<title>Examples</title>