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help / color / mirror / Atom feedFrom: Ashutosh Bapat <[email protected]>
To: Etsuro Fujita <[email protected]>
Cc: Robert Haas <[email protected]>
Cc: Rajkumar Raghuwanshi <[email protected]>
Cc: pgsql-hackers <[email protected]>
Subject: Re: Expression errors with "FOR UPDATE" and postgres_fdw with partition wise join enabled.
Date: Wed, 4 Jul 2018 15:41:35 +0530
Message-ID: <CAFjFpRfVwaxfrRi8u5LmBX-zMhyzwYdGcj2VzpoxKYWLm9Y91A@mail.gmail.com> (raw)
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On Wed, Jul 4, 2018 at 3:36 PM, Etsuro Fujita
<[email protected]> wrote:
>
> I don't produce a test case where the plan is an Append with Gather
> subplans, but I'm not sure that it's a good thing to allow us to consider
> such a plan because in that plan, each Gather would try to grab its own pool
> of workers. Am I missing something?
If the overall join can not use parallelism, having individual child
joins use parallel query might turn out to be efficient even if done
one child at a time. Parallel append drastically reduces the cases
where something like could be useful, but I don't think we can
theoretically eliminate the need for such a plan.
--
Best Wishes,
Ashutosh Bapat
EnterpriseDB Corporation
The Postgres Database Company
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Subject: Re: Expression errors with "FOR UPDATE" and postgres_fdw with partition wise join enabled.
In-Reply-To: <CAFjFpRfVwaxfrRi8u5LmBX-zMhyzwYdGcj2VzpoxKYWLm9Y91A@mail.gmail.com>
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