On Mon, Feb 3, 2014 at 01:08:44AM +0900, Fujii Masao wrote:
> On Fri, Jan 17, 2014 at 8:38 AM, Marko Tiikkaja <[email protected]> wrote:
> > Hi,
> >
> > Myself and others found this statement in the documentation about $SUBJECT
> > very confusing: "max_standby_archive_delay must be kept large in this case,
> > because delayed WAL files might already contain entries that conflict with
> > the desired standby queries.". After a chat with Andres I've tried to make
> > it clearer what said statement tries to convey.
> >
> > Did I succeed?
>
> Don't we need to increase also max_standby_streaming_delay
> in the case that you mentioned in the patch? When the standby
> successfully reconnects to the master, lots of WAL files would
> be streamed and they might already have WAL entries that
> conflict with standby queries. No?
I have developed the attached doc patch to improve the wording on this
topic.
--
Bruce Momjian <[email protected]> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ Everyone has their own god. +
diff --git a/doc/src/sgml/high-availability.sgml b/doc/src/sgml/high-availability.sgml
new file mode 100644
index ecb51c4..39d7467
*** a/doc/src/sgml/high-availability.sgml
--- b/doc/src/sgml/high-availability.sgml
*************** if (!triggered)
*** 1889,1897 ****
situation will be no worse than if the standby queries were running
directly on the primary server, and you are still getting the benefit of
off-loading execution onto the standby.
! <varname>max_standby_archive_delay</> must be kept large in this case,
! because delayed WAL files might already contain entries that conflict with
! the desired standby queries.
</para>
<para>
--- 1889,1902 ----
situation will be no worse than if the standby queries were running
directly on the primary server, and you are still getting the benefit of
off-loading execution onto the standby.
! If standby servers connect and disconnect frequently, you
! might want to make adjustments to handle the period when
! <varname>hot_standby_feedback</> feedback is not being provided.
! For example, consider increasing <varname>max_standby_archive_delay</>
! so that queries are not rapidly cancelled by conflicts in WAL archive
! files during disconnected periods. You should also consider increasing
! <varname>max_standby_streaming_delay</> to avoid rapid cancellations
! by newly-arrived streaming WAL entries after reconnection.
</para>
<para>
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