Re: increasing query time after analyze

Hello

2014-02-05 Katharina Koobs <katharina(dot)koobs(at)uni-konstanz(dot)de>:

> Hi,
>
>
>
> We have a PostgreSQL DB, version 9.3 on a Suse Linux system.
>
> We ran the update from postgresql 8.4 to 9.3.
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> After importing the database the query time of one sql query is about 30
> sec.
>
> After ANALYZE the DB the query time of this sql query is about 45 minutes.
>
> We can see that after analyzing the indexes will no longer be used.
>
>
>
> Has anyone an idea why ANALYZE cause this problem?
>

yes, it is possible - sometimes due more reasons (some strange dataset or
correlation between columns) a statistics estimations are totally out. And
bad musty statistics can produces better estimations than fresh statistics

please send a "EXPLAIN ANALYZE" output for fast and slow queries.

Regards

Pavel Stehule

>
>
> Thanks a lot for your help!
>
>
>
> Katharina
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>
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>