From: | Cédric Villemain <cedric(dot)villemain(at)dalibo(dot)com> |
---|---|
To: | Bill Moran <wmoran(at)collaborativefusion(dot)com> |
Cc: | "Campbell, Lance" <lance(at)uiuc(dot)edu>, pgsql-performance(at)postgresql(dot)org |
Subject: | Re: work_mem and shared_buffers |
Date: | 2007-11-12 10:17:57 |
Message-ID: | 47382855.1090902@dalibo.com |
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Thread: | |
Lists: | pgsql-performance |
Bill Moran a écrit :
> On Fri, 9 Nov 2007 12:08:57 -0600
> "Campbell, Lance" <lance(at)uiuc(dot)edu> wrote:
>
>
>> How do you know when you should up the value of work_mem? Just play
>> with the number. Is there a query I could do that would tell me if
>> PostgreSql is performing SQL that could use more memory for sorting?
>>
>
> 8.2 and older, it can be difficult to know, and I don't have a specific
> recommendation.
>
>
I haven't use it in that context before, but perhaps inotify can be used
to catch postgresql usage of temp files. ( http://inotify.aiken.cz/ ,
http://inotify.aiken.cz/?section=incron&page=about&lang=en )
> 8.3 includes a parameter to log the usage of temporary files by Postgres.
> When a sort can't fit in the available memory, it uses a temp file, thus
> you could use this new feature to track when sorts don't fit in
> work_mem.
>
>
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