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Re: explain analyze output with parallel workers - question about meaning of information for explain.depesz.com

Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>

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From: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: Hubert Lubaczewski <depesz@depesz.com>, pgsql-hackers mailing list <pgsql-hackers@postgresql.org>
Date: 2017-11-27T08:34:00Z
Lists: pgsql-hackers 
On Sat, Nov 25, 2017 at 7:08 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:
>>
>> It looks that the actual time is really actual time, and loops is
>> "worker nodes + 1".
>>
>> Is that really the case?
>>
>
> I think so.
>

To add to what Amit has explained. The + 1 is for the leader (the
backend running the whole query) which also runs the parallel plan if
it gets time between fetching rows from the workers.


-- 
Best Wishes,
Ashutosh Bapat
EnterpriseDB Corporation
The Postgres Database Company

Commits

  1. Back-port fix for accumulation of parallel worker instrumentation.

  2. Test instrumentation of Hash nodes with parallel query.

  3. Try again to fix accumulation of parallel worker instrumentation.

  4. Revert "Fix accumulation of parallel worker instrumentation."

  5. Fix accumulation of parallel worker instrumentation.