| From: | Andres Freund <andres(at)2ndquadrant(dot)com> |
|---|---|
| To: | Дмитрий Дегтярёв <degtyaryov(at)gmail(dot)com> |
| Cc: | Merlin Moncure <mmoncure(at)gmail(dot)com>, postgres performance list <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Cpu usage 100% on slave. s_lock problem. |
| Date: | 2013-09-17 11:59:26 |
| Message-ID: | 20130917115926.GA5452@awork2.anarazel.de |
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| Lists: | pgsql-performance |
Hi,
On 2013-09-17 17:55:01 +0600, Дмитрий Дегтярёв wrote:
> We have not been able to reproduce this problem on a test servers. Use this
> patch to production servers do not dare.
>
> In the course of studying the problems we have identified that many queries
> are executed on the slave several times slower. On master function
> heap_hot_search_buffer execute 100 cycles, on the slave the same query with
> the same plan function heap_hot_search_buffer execute 2000 cycles.
> Also, we were able to reproduce the problem on the master and detect that
> there s_lock of slow queries.
What you describe is normally an indication that you have too many
longrunning transactions around preventing hot pruning from working.
Greetings,
Andres Freund
--
Andres Freund http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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