From: hubert depesz lubaczewski <depesz@depesz.com>
To: pgsql-hackers mailing list <pgsql-hackers@postgresql.org>
Subject: explain analyze output with parallel workers - question about meaning of information for explain.depesz.com
Date: Fri, 24 Nov 2017 12:21:51 +0100
Message-ID: <20171124112151.GA6616@depesz.com> (raw)
Hi,
up to parallel executions, when we had node in explain analyze showing
"loops=x" with x more than 1, it meant that the "actual time" had to be
multiplied by loops to get real time spent in a node.
For example, check step 13 in https://explain.depesz.com/s/gNBd
It shows time of 3ms, but loops of 1873, so the actual time is ~ 5600ms.
But with parallel execution it seems to be no longer the case.
For example:
https://explain.depesz.com/s/LTMp
or
https://explain.depesz.com/s/QHRi
It looks that the actual time is really actual time, and loops is
"worker nodes + 1".
Is that really the case? Should I, for explain.depesz.com, when dealing
with partial* and parallel* nodes, use "loops=1" for calculation of
exclusive/inclusive time? always? some other nodes?
or am I missing something in here?
Best regards,
depesz
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To: pgsql-hackers@postgresql.org
Cc: depesz@depesz.com
Subject: Re: explain analyze output with parallel workers - question about meaning of information for explain.depesz.com
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