From: Tom Lane <tgl@sss.pgh.pa.us>
To: Mathieu Fenniak <mathieu.fenniak@replicon.com>
cc: Andres Freund <andres@anarazel.de>, pgsql-general@postgresql.org
Subject: Re: Logical decoding CPU-bound w/ large number of tables
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Comments: In-reply-to Mathieu Fenniak <mathieu.fenniak@replicon.com>
	message dated "Fri, 12 May 2017 14:19:10 -0600"
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Date: Fri, 12 May 2017 16:32:41 -0400
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Mathieu Fenniak <mathieu.fenniak@replicon.com> writes:
> I've taken your patches, Tom, and applied them to a test deployment of my
> actual application.

> The most accessible way I have to reproduce this issue is to run a
> maintenance task that we typically run during a software deployment, which
> will remove some tenant schemas from our database system.  I ran that task
> with and without the patches, and monitored how long logical replication
> stalled.  This test was on a database with 22 schemas containing 400 tables
> each (~8800 tables).

> As a baseline, PostgreSQL 9.5.6 stalled completely for 21m 13s

> PostgreSQL 9.5.6 + all three patches stalled completely for 4m 11s.

> Definitely a fantastic improvement. :-)

Thanks for confirming that these patches help in a real-world scenario.
Obviously there's still room for improvement, but I think it's worth
pushing what I've done, so I'll go do that.  I hope Andres will follow
up with trying to improve matters from the other angle.

			regards, tom lane


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