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Improve documentation of log rotation options, per Ed L.

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This commit is contained in:
Tom Lane 2004-09-17 22:40:46 +00:00
parent 915351e9c7
commit f6d278364e
1 changed files with 30 additions and 11 deletions
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41
doc/src/sgml/runtime.sgml
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@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.280 2004/08/31 04:53:43 tgl Exp $
$PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.281 2004/09/17 22:40:46 tgl Exp $
-->
<Chapter Id="runtime">
@ -1929,16 +1929,16 @@ archive_command = 'copy "%p" /mnt/server/archivedir/"%f"' # Win32
<term><varname>log_filename</varname> (<type>string</type>)</term>
<listitem>
<para>
When <varname>redirect_stderr</> is enabled, this option
When <varname>redirect_stderr</varname> is enabled, this option
sets the file names of the created log files. The value
is treated as a <systemitem>strftime</> pattern,
so <literal>%</>-escapes
is treated as a <systemitem>strftime</systemitem> pattern,
so <literal>%</literal>-escapes
can be used to specify time-varying file names.
If no <literal>%</>-escapes are present,
If no <literal>%</literal>-escapes are present,
<productname>PostgreSQL</productname> will
append the epoch of the new log file's open time. For example,
if <varname>log_filename</> were <literal>server_log</>, then the
chosen file name would be <literal>server_log.1093827753</>
if <varname>log_filename</varname> were <literal>server_log</literal>, then the
chosen file name would be <literal>server_log.1093827753</literal>
for a log starting at Sun Aug 29 19:02:33 2004 MST.
This option can only be set at server start or in the
<filename>postgresql.conf</filename> configuration file.
@ -1950,7 +1950,7 @@ archive_command = 'copy "%p" /mnt/server/archivedir/"%f"' # Win32
<term><varname>log_rotation_age</varname> (<type>integer</type>)</term>
<listitem>
<para>
When <varname>redirect_stderr</> is enabled, this option
When <varname>redirect_stderr</varname> is enabled, this option
determines the maximum lifetime of an individual log file.
After this many minutes have elapsed, a new log file will
be created. Set to zero to disable time-based creation of
@ -1965,7 +1965,7 @@ archive_command = 'copy "%p" /mnt/server/archivedir/"%f"' # Win32
<term><varname>log_rotation_size</varname> (<type>integer</type>)</term>
<listitem>
<para>
When <varname>redirect_stderr</> is enabled, this option
When <varname>redirect_stderr</varname> is enabled, this option
determines the maximum size of an individual log file.
After this many kilobytes have been emitted into a log file,
a new log file will be created. Set to zero to disable size-based
@ -1980,19 +1980,38 @@ archive_command = 'copy "%p" /mnt/server/archivedir/"%f"' # Win32
<term><varname>log_truncate_on_rotation</varname> (<type>boolean</type>)</term>
<listitem>
<para>
When <varname>redirect_stderr</> is enabled, this option will cause
When <varname>redirect_stderr</varname> is enabled, this option will cause
<productname>PostgreSQL</productname> to truncate (overwrite),
rather than append to, any existing log file of the same name.
However, truncation will occur only when a new file is being opened
due to time-based rotation, not during server startup or size-based
rotation. When false, pre-existing files will be appended to in
all cases. For example, using this option in combination with
a <varname>log_filename</> like <literal>postgresql-%H.log</>
a <varname>log_filename</varname> like <literal>postgresql-%H.log</literal>
would result in generating twenty-four hourly log files and then
cyclically overwriting them.
This option can only be set at server start or in the
<filename>postgresql.conf</filename> configuration file.
</para>
<para>
Example: To keep 7 days of logs, one log file per day named
<literal>server_log.Mon</literal>, <literal>server_log.Tue</literal>,
etc, and automatically overwrite last week's log with this week's log,
set <varname>log_filename</varname> to <literal>server_log.%a</literal>,
<varname>log_truncate_on_rotation</varname> to <literal>true</literal>, and
<varname>log_rotation_age</varname> to <literal>1440</literal>.
</para>
<para>
Example: To keep 24 hours of logs, one log file per hour, but
also rotate sooner if the log file size exceeds 1GB, set
<varname>log_filename</varname> to <literal>server_log.%H%M</literal>,
<varname>log_truncate_on_rotation</varname> to <literal>true</literal>,
<varname>log_rotation_age</varname> to <literal>60</literal>, and
<varname>log_rotation_size</varname> to <literal>1000000</literal>.
Including <literal>%M</> in <varname>log_filename</varname> allows
any size-driven rotations that may occur to select a filename
different from the hour's initial filename.
</para>
</listitem>
</varlistentry>