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Re: Query much slower after upgrade to 9.6.1 - Mailing list pgsql-performance

From Adam Brusselback
Subject Re: Query much slower after upgrade to 9.6.1
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Msg-id CAMjNa7dR-QiteVCW+scjg7H7-+=vVSprm+pyr4Ffq=6=kVfTHQ@mail.gmail.com
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In response to Re: Query much slower after upgrade to 9.6.1  (Tom Lane <tgl@sss.pgh.pa.us>)
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Did you pay attention to the estimated number of groups (ie, estimated
output rowcount for the aggregation plan node) while fooling around with
the statistics?  How does it compare to reality, and to 9.5's estimate?

I'm re-doing the tests and paying attention to that now.

With statistics = 100, the under / over estimations change only slightly. Nothing that drastically alters anything: https://explain.depesz.com/s/GEWy
With statistics = 1000 pretty much the same as above: https://explain.depesz.com/s/6CWM

So between 9.5.5, 9.6.1, none of the stats changed in a noticeable way. Changing the statistics target on 9.6.1 slightly altered the estimates, but nothing to write home about.
All have some significant deviations from actual row counts in the part of the query which is making the query slow.

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