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help / color / mirror / Atom feedFrom: johannes graën <johannes@selfnet.de>
To: pgsql-performance@postgresql.org
Subject: performance drop after upgrade (9.6 > 10)
Date: Wed, 11 Oct 2017 13:06:46 +0200
Message-ID: <CA++JNSeCW1BSRVS7N--OmVOMDiMVA61_DFMA24fFbM2R7JdQjQ@mail.gmail.com> (raw)
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Hi,
I wrote a query that joins several tables usually returning less than
1000 rows, groups them and generates a JSON object of the result. In
9.6 is was a question of milliseconds for that query to return the
requested data. Now, after upgrading to 10, the query never returns -
at least it hasn't returned in the last hour.
To see what happens, I requested the query plan [1]. It looks complex
and shows a lot of parallelization. I don't have the query plan from
9.6, but I remember it being considerably simpler.
Can anyone have a guess what altered the performance here so
dramatically? Is there a way to disable new parallelization features
just for this query to see if it makes any difference?
Best
Johannes
[1] https://explain.depesz.com/s/xsPP
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To: pgsql-performance@postgresql.org
Cc: johannes@selfnet.de
Subject: Re: performance drop after upgrade (9.6 > 10)
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