Re: Postgres Replaying WAL slowly - Mailing list pgsql-performance

From Jeff Frost
Subject Re: Postgres Replaying WAL slowly
Date
Msg-id 2E438E7D-E3C1-47A1-A1AF-9FE50A14A302@pgexperts.com
Whole thread Raw
In response to Re: Postgres Replaying WAL slowly  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: Postgres Replaying WAL slowly
List pgsql-performance
On Jun 30, 2014, at 1:39 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:

>
>
>> Another item of note is the system catalogs are quite bloated:
>> Would that cause the replica to spin on StandbyReleaseLocks?
>
> AFAIK, no.  It's an unsurprising consequence of heavy use of short-lived
> temp tables though.
>

Yah, this has been an issue in the past, so we tend to cluster them regularly during off-hours to minimize the issue.

> So it seems like we have a candidate explanation.  I'm a bit surprised
> that StandbyReleaseLocks would get this slow if there are only a dozen
> AccessExclusiveLocks in place at any one time, though.  Perhaps that
> was a low point and there are often many more?
>
>

Entirely possible that it was a low point.  We'll set up some monitoring to track the number of AccessExclusiveLocks
andsee how much variance there is throughout the day. 




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