Re: parallel "return query" is no good

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
Cc: "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: parallel "return query" is no good
Date: 2017-03-24 16:43:59
Message-ID: CA+TgmoZZMG9hRbC0ANBdakHyZ8-2Hpa=kKyrOFGM8c78wQx-fg@mail.gmail.com
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On Thu, Mar 23, 2017 at 1:53 PM, Alvaro Herrera
<alvherre(at)2ndquadrant(dot)com> wrote:
> Robert Haas wrote:
>> I guess the downside of back-patching this is that it could cause a
>> plan change for somebody which ends up being worse. On the whole,
>> serial execution of queries intended to be run in parallel isn't
>> likely to work out well, but it's always possible somebody has a cases
>> where it happens to be winning, and this could break it. So maybe I
>> should do this only in master? Thoughts?
>
> I think that the chances of someone depending on a parallel plan running
> serially by accident which is better than the non-parallel plan, are
> pretty slim.
>
> +1 for back-patching.

All right, done.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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