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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Josh Kupershmidt <schmiddy@gmail.com>
Cc: Greg Smith <greg@2ndquadrant.com>
Cc: Chris <lists@deksai.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: stats collector suddenly causing lots of IO
Date: Fri, 16 Apr 2010 15:22:42 -0400
Message-ID: <13663.1271445762@sss.pgh.pa.us> (raw)
In-Reply-To: <m2w4ec1cf761004161135ka272c184u2f0dd8a0c8460d5d@mail.gmail.com>
References: <20100413170105.GA29571@chris-laptop.a2hosting.com>
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Josh Kupershmidt <schmiddy@gmail.com> writes:
>         name         | current_setting |       source
> ----------------------+-----------------+--------------------
>  vacuum_cost_delay    | 200ms           | configuration file
>  vacuum_cost_limit    | 100             | configuration file
>  vacuum_cost_page_hit | 6               | configuration file
> 
> It looks like the default which I have of autovacuum_vacuum_cost_limit
> = -1, which means it's inheriting the vacuum_cost_limit of 100 I had
> set. I'll try bumping vacuum_cost_limit up to 1000 or so.

Actually I think the main problem is that cost_delay value, which is
probably an order of magnitude too high.  The way to limit vacuum's
I/O impact on other stuff is to make it take frequent short delays,
not have it run full speed and then sleep a long time.  In any case,
your current settings have got it sleeping way too much.  Two WEEKS !!!??

			regards, tom lane



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