Date: Mon, 30 Mar 2020 00:52:43 +0200
From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
To: Andres Freund <andres@anarazel.de>
Cc: Alexander Korotkov <a.korotkov@postgrespro.ru>,
	Peter Geoghegan <pg@bowt.ie>,
	PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Subject: Re: Improving connection scalability: GetSnapshotData()
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On Sun, Mar 29, 2020 at 11:50:10AM -0700, Andres Freund wrote:
>Hi,
>
>On March 29, 2020 11:24:32 AM PDT, Alexander Korotkov
><a.korotkov@postgrespro.ru> wrote:
>> clearly a big win on majority
>>of workloads, I think we still need to investigate different workloads
>>on different hardware to ensure there is no regression.
>
>Definitely. Which workloads are you thinking of? I can think of those
>affected facets: snapshot speed, commit speed with writes, connection
>establishment, prepared transaction speed. All in the small and large
>connection count cases.
>
>I did measurements on all of those but prepared xacts, fwiw. That
>definitely needs to be measured, due to the locking changes around
>procarrayaddd/remove.
>
>I don't think regressions besides perhaps 2pc are likely - there's
>nothing really getting more expensive but procarray add/remove.
>

If I get some instructions what tests to do, I can run a bunch of tests
on my machinees (not the largest boxes, but at least something). I don't
have the bandwidth to come up with tests on my own, at the moment.

regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services