Re: parallel explain analyze support not exercised

From: Rafia Sabih <rafia(dot)sabih(at)enterprisedb(dot)com>
To: Andres Freund <andres(at)anarazel(dot)de>
Cc: PostgreSQL Developers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: parallel explain analyze support not exercised
Date: 2017-04-03 04:56:27
Message-ID: CAOGQiiP40h86uAnbTEN-KyDEsDG1dZV6yyEFZPLaWyivjwDw5A@mail.gmail.com
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On Sat, Apr 1, 2017 at 12:25 AM, Andres Freund <andres(at)anarazel(dot)de> wrote:
> Hi,
>
> As visible in [1], the explain analyze codepaths of parallel query isn't
> exercised in the tests. That used to be not entirely trivial if the
> output was to be displayed (due to timing), but we should be able to do
> that now that we have the SUMMARY option.
>
> E.g.
> SET max_parallel_workers = 0;
> EXPLAIN (analyze, timing off, summary off, costs off) SELECT * FROM blarg2 WHERE generate_series < 0;
> ┌───────────────────────────────────────────────────────────┐
> │ QUERY PLAN │
> ├───────────────────────────────────────────────────────────┤
> │ Gather (actual rows=0 loops=1) │
> │ Workers Planned: 10 │
> │ Workers Launched: 0 │
> │ -> Parallel Seq Scan on blarg2 (actual rows=0 loops=1) │
> │ Filter: (generate_series < 0) │
> │ Rows Removed by Filter: 10000000 │
> └───────────────────────────────────────────────────────────┘
>
> should be reproducible. I'd suggest additionally adding one tests that
> throws the EXPLAIN output away, but actually enables paralellism.
>
> Greetings,
>
> Andres Freund
>
> [1] https://coverage.postgresql.org/src/backend/executor/execParallel.c.gcov.html

Please find the attached for the same.

--
Regards,
Rafia Sabih
EnterpriseDB: http://www.enterprisedb.com/

Attachment Content-Type Size
code_coverage.patch application/octet-stream 1.4 KB

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