On 26 February 2014 13:32, Simon Riggs <si...@2ndquadrant.com> wrote:
> On 26 February 2014 13:07, Thom Brown <t...@linux.com> wrote:
> > On 19 December 2013 19:33, Simon Riggs <si...@2ndquadrant.com> wrote:
> >>
> >> On 19 December 2013 19:19, Thom Brown <t...@linux.com> wrote:
> >> > On 12 December 2013 10:56, Simon Riggs <si...@2ndquadrant.com> wrote:
> >> >> Allow time delayed standbys and recovery
> >> >>
> >> >> Set min_recovery_apply_delay to force a delay in recovery apply for
> >> >> commit and
> >> >> restore point WAL records. Other records are replayed immediately.
> >> >> Delay is
> >> >> measured between WAL record time and local standby time.
> >> >>
> >> >> Robert Haas, FabrÃzio de Royes Mello and Simon Riggs
> >> >> Detailed review by Mitsumasa Kondo
> >> >
> >> > Could a note be added about the additional disk space requirements for
> >> > WAL on the standby? If one is delaying replay, WAL files created over
> >> > the delayed period will build up in pg_xlog on the standby until
> >> > they're consumed upon replay, so considerations about storing those
> >> > additional files will need to be made. It may otherwise trip up
> >> > anyone who, say, delays replay by 24 hours in a busy production
> >> > environment, and finds they have run out of disk space and no longer
> >> > have a valid standby.
> >>
> >> Thanks Thom, good point. I will add a note to the docs.
> >
> >
> > Just a reminder that this note hasn't been added to the docs yet.
>
> Please cut a doc patch and I'll apply.
Attached.
--
Thom
diff --git a/doc/src/sgml/recovery-config.sgml b/doc/src/sgml/recovery-config.sgml
index b69ce28..813db5f 100644
--- a/doc/src/sgml/recovery-config.sgml
+++ b/doc/src/sgml/recovery-config.sgml
@@ -182,6 +182,12 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"' # Windows
the standby will end recovery without further waiting.
</para>
<para>
+ WAL records generated over the delay period need to be stored on the
+ standby until they can be applied. Therefore long delays can result in
+ a build-up of WAL files, increasing disk space requirements for the
+ <filename>pg_xlog</> directory.
+ </para>
+ <para>
This parameter is intended for use with streaming replication deployments,
however, if the parameter is specified it will be honoured in all cases.
Synchronous replication is not affected by this setting because there is
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