-<!-- $Header: /cvsroot/pgsql/doc/src/sgml/ref/checkpoint.sgml,v 1.1 2001/01/13 03:11:12 petere Exp $ -->
+<!-- $Header: /cvsroot/pgsql/doc/src/sgml/ref/checkpoint.sgml,v 1.2 2001/01/24 21:56:23 petere Exp $ -->
<refentry id="sql-checkpoint">
<docinfo>
- <date>2001-01-13</date>
+ <date>2001-01-24</date>
</docinfo>
<refmeta>
<refnamediv>
<refname>CHECKPOINT</refname>
- <refpurpose>Force transaction log to disk</refpurpose>
+ <refpurpose>Force transaction log checkpoint</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>Description</title>
<para>
- This documentation needs to be written.
+ Write-Ahead Logging (WAL) puts a checkpoint in the transaction log
+ every 300 seconds by default. (This may be changed by the run-time
+ configuration option <parameter>CHECKPOINT_TIMEOUT</parameter>.)
+ The <command>CHECKPOINT</command> command forces a checkpoint at
+ the point at which the command is issued. The next automatic
+ checkpoint will still happen after the original cycle expires.
+ </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 the
+ <citetitle>PostgreSQL Administrator's Guide</citetitle> for more
+ information about the WAL system.
</para>
</refsect1>