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From: John Scalia <jayknowsunix@gmail.com>
Mime-Version: 1.0 (1.0)
Date: Wed, 30 Dec 2020 16:38:31 -0500
Subject: Creating a materialized view causing blocks
Message-Id: <52BF172F-FF9F-4DAC-A9E4-A540D3E84D5E@gmail.com>
To: pgsql-admin <pgsql-admin@postgresql.org>
Precedence: bulk

Over last evening, one of my colleagues had begun recreating a materialized v=
iew. =46rom looking at his code, it was only doing some selects, like one wo=
uld expect, however, several API clients ended up being blocked by this, and=
 I=E2=80=99m attempting to understand why. I should note that a couple of th=
e tables used here, contained more than 100 million rows, and I=E2=80=99m wo=
ndering if the system simply gave up trying to keep the view=E2=80=99s data c=
onsistency on par, and if a more than a non-exclusive read block was then im=
posed. The API=E2=80=99s involved basically kept getting respawned, and at o=
ne point there were more than 4000 attempted simultaneous connections. Not a=
 lot of fun, but fortunately for me, the application team only called the ot=
her DBA to fix the issue. I=E2=80=99d still like to know what happened.
=E2=80=94
Jay

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