| From: | Jeff Frost <jeff(at)pgexperts(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Andres Freund <andres(at)2ndquadrant(dot)com>, Matheus de Oliveira <matioli(dot)matheus(at)gmail(dot)com>, Soni M <diptatapa(at)gmail(dot)com>, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, pgsql-performance <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Postgres Replaying WAL slowly |
| Date: | 2014-06-30 20:46:05 |
| Message-ID: | 2E438E7D-E3C1-47A1-A1AF-9FE50A14A302@pgexperts.com |
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| Lists: | pgsql-performance |
On Jun 30, 2014, at 1:39 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)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 and see how much variance there is throughout the day.
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