| From: | Bill Moran <wmoran(at)collaborativefusion(dot)com> |
|---|---|
| To: | "Campbell, Lance" <lance(at)uiuc(dot)edu> |
| Cc: | pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: work_mem and shared_buffers |
| Date: | 2007-11-09 20:08:09 |
| Message-ID: | 20071109150809.e75af5b3.wmoran@collaborativefusion.com |
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| Lists: | pgsql-performance |
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.
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.
--
Bill Moran
Potential Technologies
http://www.potentialtech.com
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