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Minor improvements to the description of archive_timeout.

This commit is contained in:
Neil Conway 2006-11-12 05:12:42 +00:00
parent a46ca619f8
commit 2b5fedc0d7
1 changed files with 16 additions and 18 deletions
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34
doc/src/sgml/config.sgml
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@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.94 2006/11/05 22:42:07 tgl Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.95 2006/11/12 05:12:42 neilc Exp $ -->
<chapter Id="runtime-config">
<title>Server Configuration</title>
@ -1601,24 +1601,22 @@ archive_command = 'copy "%p" /mnt/server/archivedir/"%f"' # Windows
</indexterm>
<listitem>
<para>
The <xref linkend="guc-archive-command"> is only invoked on completed
WAL segments. Hence,
if your server generates only little WAL traffic (or has slack periods
where it does so), there could be a long delay between the completion
of a transaction and its safe recording in archive storage. To put
a limit on how old unarchived data can be, you can set
<varname>archive_timeout</> to force the server to switch
to a new WAL segment file periodically. When this parameter is
greater than zero, the server will switch to a new segment file
whenever this many seconds elapse since the last segment file switch.
Note that archived
files that are closed early due to a forced switch are still the same
length as completely full files. It is therefore unwise to set a very
short <varname>archive_timeout</> &mdash; it will bloat your archive
The <xref linkend="guc-archive-command"> is only invoked on
completed WAL segments. Hence, if your server generates little WAL
traffic (or has slack periods where it does so), there could be a
long delay between the completion of a transaction and its safe
recording in archive storage. To put a limit on how old unarchived
data can be, you can set <varname>archive_timeout</> to force the
server to switch to a new WAL segment file periodically. When this
parameter is greater than zero, the server will switch to a new
segment file whenever this many seconds have elapsed since the last
segment file switch. Note that archived files that are closed early
due to a forced switch are still the same length as completely full
files. Therefore, it is unwise to use a very short
<varname>archive_timeout</> &mdash; it will bloat your archive
storage. <varname>archive_timeout</> settings of a minute or so are
usually reasonable.
This parameter can only be set in the <filename>postgresql.conf</>
file or on the server command line.
usually reasonable. This parameter can only be set in the
<filename>postgresql.conf</> file or on the server command line.
</para>
</listitem>
</varlistentry>