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Re: increasing query time after analyze - Mailing list pgsql-performance

From Pavel Stehule
Subject Re: increasing query time after analyze
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Msg-id CAFj8pRBu_Yt19J1qXcDsGmSgCatW-WdjKoCnHgSE3h_NfAXEMA@mail.gmail.com
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In response to increasing query time after analyze  ("Katharina Koobs" <katharina.koobs@uni-konstanz.de>)
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Hello


2014-02-05 Katharina Koobs <katharina.koobs@uni-konstanz.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.

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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