Horton

Re: Parallel execution and prepared statements

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Albe Laurenz <laurenz.albe@wien.gv.at>, Tobias Bussmann <t.bussmann@gmx.net>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2016-12-01T12:57:26Z
Lists: pgsql-hackers

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  1. Enable parallelism for prepared statements and extended query protocol.

On Wed, Nov 30, 2016 at 11:57 PM, Robert Haas <robertmhaas@gmail.com> wrote:
> On Tue, Nov 29, 2016 at 6:24 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:
>>
>> Robert, do you have any better ideas for this problem?
>
> Not really.  I think your prepared_stmt_parallel_query_v2.patch is
> probably the best approach proposed so far, but I wonder why we need
> to include DestCopyOut and DestTupleStore.  DestIntoRel and
> DestTransientRel both write to an actual relation, which is a problem
> for parallel mode, but I think the others don't.
>

I have tried to restrict all the non-readonly operation modes or modes
where parallelism might not make sense like DestTupleStore.  If we
want to just prohibit the cases where it can fail now, then I think
prohibiting only DestIntoRel should be sufficient because that is a
case where the user is allowed to do DDL for an already prepared read
only statement like Create Table AS .. EXECUTE.

-- 
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com