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[GENERAL] Performance degradation when using auto_explain - Mailing list pgsql-general

From Kisung Kim
Subject [GENERAL] Performance degradation when using auto_explain
Date
Msg-id CABF0Rr2U1gi3=iXvGfEm_EnbAauXXSKf26GMEKubGp3k5R1yjQ@mail.gmail.com
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Responses Re: [GENERAL] Performance degradation when using auto_explain  (Andreas Kretschmer <akretschmer@spamfence.net>)
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Hi,

I found performance degradation when using auto_explain with log_analyze option true.
It automatically logs query plan analyze results.

But when there are many concurrent sessions, the performance degrades in proportion to the number of concurrent sessions.
These queries are all read-only queries.
And I found that the time consumed in a plan node like IndexScan takes more times when there are many sessions.

At first, I thought that it may be due to CPU scheduling contentions incurs the degradation.
But there are more CPU cores than the session counts.

And finally I found that auto_explain is the cause of the problem.

I am curious now, why auto_explain incurs contentions between the session?
I use Ubuntu linux. Is it a problem of gettimeofday()?

Thank you.

Kisung Kim
--

                                                                                                                                                       

Bitnine Global Inc., Kisung Kim, Ph.D
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