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Minor improvements in backup and recovery:

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- create a separate archive_mode GUC, on which archive_command is dependent

- %r option in recovery.conf sends last restartpoint to recovery command

- %r used in pg_standby, updated README

- minor other code cleanup in pg_standby

- doc on Warm Standby now mentions pg_standby and %r

- log_restartpoints recovery option emits LOG message at each restartpoint

- end of recovery now displays last transaction end time, as requested
  by Warren Little; also shown at each restartpoint

- restart archiver if needed to carry away WAL files at shutdown

Simon Riggs
This commit is contained in:
Tom Lane
2007-09-26 22:36:30 +00:00
parent 80963144ad
commit f18dfc4835
12 changed files with 356 additions and 118 deletions
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20
doc/src/sgml/perform.sgml
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@@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/perform.sgml,v 1.64 2007/03/29 00:15:36 tgl Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/perform.sgml,v 1.65 2007/09/26 22:36:30 tgl Exp $ -->
<chapter id="performance-tips">
<title>Performance Tips</title>
@@ -819,7 +819,7 @@ SELECT * FROM x, y, a, b, c WHERE something AND somethingelse;
needs to be written, because in case of an error, the files
containing the newly loaded data will be removed anyway.
However, this consideration does not apply when
<xref linkend="guc-archive-command"> is set, as all commands
<xref linkend="guc-archive-mode"> is set, as all commands
must write WAL in that case.
</para>
@@ -892,22 +892,24 @@ SELECT * FROM x, y, a, b, c WHERE something AND somethingelse;
</sect2>
<sect2 id="populate-pitr">
<title>Turn off <varname>archive_command</varname></title>
<title>Turn off <varname>archive_mode</varname></title>
<para>
When loading large amounts of data into an installation that uses
WAL archiving, you might want to disable archiving (unset the
<xref linkend="guc-archive-command"> configuration variable)
WAL archiving, you might want to disable archiving (turn off the
<xref linkend="guc-archive-mode"> configuration variable)
while loading. It might be
faster to take a new base backup after the load has completed
than to process a large amount of incremental WAL data.
But note that turning <varname>archive_mode</varname> on or off
requires a server restart.
</para>
<para>
Aside from avoiding the time for the archiver to process the WAL data,
doing this will actually make certain commands faster, because they
are designed not to write WAL at all if <varname>archive_command</varname>
is unset. (They can guarantee crash safety more cheaply by doing an
are designed not to write WAL at all if <varname>archive_mode</varname>
is off. (They can guarantee crash safety more cheaply by doing an
<function>fsync</> at the end than by writing WAL.)
This applies to the following commands:
<itemizedlist>
@@ -989,8 +991,8 @@ SELECT * FROM x, y, a, b, c WHERE something AND somethingelse;
<listitem>
<para>
If using WAL archiving, consider disabling it during the restore.
To do that, unset <varname>archive_command</varname> before loading the
dump script, and afterwards restore <varname>archive_command</varname>
To do that, turn off <varname>archive_mode</varname> before loading the
dump script, and afterwards turn it back on
and take a fresh base backup.
</para>
</listitem>