| <!-- $PostgreSQL: pgsql/doc/src/sgml/ref/checkpoint.sgml,v 1.16 2008/11/14 10:22:45 petere Exp $ --> |
| |
| <refentry id="sql-checkpoint"> |
| <refmeta> |
| <refentrytitle id="sql-checkpoint-title">CHECKPOINT</refentrytitle> |
| <manvolnum>7</manvolnum> |
| <refmiscinfo>SQL - Language Statements</refmiscinfo> |
| </refmeta> |
| |
| <refnamediv> |
| <refname>CHECKPOINT</refname> |
| <refpurpose>force a transaction log checkpoint</refpurpose> |
| </refnamediv> |
| |
| <indexterm zone="sql-checkpoint"> |
| <primary>CHECKPOINT</primary> |
| </indexterm> |
| |
| <refsynopsisdiv> |
| <synopsis> |
| CHECKPOINT |
| </synopsis> |
| </refsynopsisdiv> |
| |
| <refsect1> |
| <title>Description</title> |
| |
| <para> |
| Write-Ahead Logging (WAL) puts a checkpoint in the transaction log |
| every so often. (To adjust the automatic checkpoint interval, see |
| the run-time configuration options <xref linkend="guc-checkpoint-segments"> |
| and <xref linkend="guc-checkpoint-timeout">.) The |
| <command>CHECKPOINT</command> command forces an immediate |
| checkpoint when the command is issued, without waiting for a |
| scheduled checkpoint. |
| </para> |
| |
| <para> |
| A checkpoint is a point in the transaction log sequence at which |
| all data files have been updated to reflect the information in the |
| log. All data files will be flushed to disk. Refer to |
| <xref linkend="wal"> for more information about the WAL system. |
| </para> |
| |
| <para> |
| Only superusers can call <command>CHECKPOINT</command>. The command is |
| not intended for use during normal operation. |
| </para> |
| </refsect1> |
| |
| <refsect1> |
| <title>Compatibility</title> |
| |
| <para> |
| The <command>CHECKPOINT</command> command is a |
| <productname>PostgreSQL</productname> language extension. |
| </para> |
| </refsect1> |
| </refentry> |