| From: | John A Meinel <john(at)arbash-meinel(dot)com> |
|---|---|
| To: | Sebastian Hennebrueder <usenet(at)laliluna(dot)de> |
| Cc: | pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Recommendations for set statistics |
| Date: | 2005-05-13 03:36:01 |
| Message-ID: | 428420A1.9090707@arbash-meinel.com |
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| Thread: | |
| Lists: | pgsql-performance |
Sebastian Hennebrueder wrote:
> Hello,
>
> I could not find any recommandations for the level of set statistics and
> what a specific level does actually mean.
> What is the difference between 1, 50 and 100? What is recommanded for a
> table or column?
>
Default I believe is 10. The higher the number, the more statistics are
kept, with a maximum of 1000.
The default is a little bit low for columns used in foreign keys, though
frequently it is okay.
When problems start, try setting them to 100 or 200. Higher is more
accurate, but takes longer to compute, *and* takes longer when planning
the optimal query method. It can be worth it, though.
John
=:->
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