From: Mike Schanne <mschanne@kns.com>
To: 'pgsql-performance@postgresql.org' <pgsql-performance@postgresql.org>
Subject: autovacuum locking question
Date: Thu, 5 Dec 2019 17:46:19 +0000
Message-ID: <0871fcf35ceb4caa8a2204ca9c38e330@USEPRDEX1.corp.kns.com> (raw)
Hi,
I am investigating a performance problem in our application and am seeing something unexpected in the postgres logs regarding the autovacuum.
2019-12-01 13:05:39.029 UTC,"wb","postgres",6966,"127.0.0.1:53976",5ddbd990.1b36,17099,"INSERT waiting",2019-11-25 13:39:28 UTC,12/1884256,12615023,LOG,00000,"process 6966 still waiting for RowExclusiveLock on relation 32938 of database 32768 after 1000.085 ms","Process holding the lock: 6045. Wait queue: 6966.",,,,,"INSERT INTO myschema.mytable (...) VALUES (...) RETURNING process.mytable.mytable_id",13,,""
2019-12-01 13:05:39.458 UTC,,,6045,,5de3b800.179d,1,,2019-12-01 12:54:24 UTC,10/417900,0,ERROR,57014,"canceling autovacuum task",,,,,"automatic vacuum of table ""postgres.myschema.mytable""",,,,""
My understanding from reading the documentation was that a vacuum can run concurrently with table inserts/updates, but from reading the logs it appears they are conflicting over a row lock. This particular table gets very frequent inserts/updates (10-100 inserts / sec) so I am concerned that if the autovacuum is constantly canceled, then the table never gets cleaned and its performance will continue to degrade over time. Is it expected for the vacuum to be canceled by an insert in this way?
We are using postgres 9.6.10.
Thanks,
Mike
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To: pgsql-performance@postgresql.org
Cc: mschanne@kns.com
Subject: Re: autovacuum locking question
In-Reply-To: <0871fcf35ceb4caa8a2204ca9c38e330@USEPRDEX1.corp.kns.com>
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