Re: stats collector suddenly causing lots of IO

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Josh Kupershmidt <schmiddy(at)gmail(dot)com>
Cc: Chris <lists(at)deksai(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: stats collector suddenly causing lots of IO
Date: 2010-04-16 15:41:24
Message-ID: 10082.1271432484@sss.pgh.pa.us
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Josh Kupershmidt <schmiddy(at)gmail(dot)com> writes:
> On Fri, Apr 16, 2010 at 11:23 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Hmm. That makes me wonder if autovacuum is functioning properly at all.
>> What does pg_stat_all_tables show for the last vacuum and analyze times
>> of those tables? Try something like
>>
>> select relname,n_live_tup,n_dead_tup,last_vacuum,last_autovacuum,last_analyze,last_autoanalyze from pg_stat_all_tables where schemaname = 'pg_catalog' order by 1;

> Output attached. Note that I ran pg_stat_reset() a few days ago.

Wow. Well, we have a smoking gun here: for some reason, autovacuum
isn't running, or isn't doing its job if it is. If it's not running
at all, that would explain failure to prune the stats collector's file
too.

Is there anything in the postmaster log that would suggest autovac
difficulties?

regards, tom lane

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