Horton

Re: Enabling parallelism for queries coming from SQL or other PL functions

Dilip Kumar <dilipbalaut@gmail.com>

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From: Dilip Kumar <dilipbalaut@gmail.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Rafia Sabih <rafia.sabih@enterprisedb.com>, PostgreSQL Developers <pgsql-hackers@postgresql.org>
Date: 2017-03-22T23:53:19Z
Lists: pgsql-hackers 
On Wed, Mar 22, 2017 at 10:33 PM, Robert Haas <robertmhaas@gmail.com> wrote:
> So couldn't we actually make this test !fcache->returnsSet || !es->lazyEval?
> That would let us allow parallel execution for all non-set-returning
> functions, and also for set-returning functions that end up with
> es->lazyEval set to false.

Yes, this is the right thing to do although we may not enable
parallelism for any more queries by adding "|| !es->lazyEval". Because
SELECT are always marked as es->lazyEval=true(And so far we have
parallelism only for select).  But here we calling the parameter to
ExecutorRun as execute_once so  !fcache->returnsSet || !es->lazyEval
is the correct one and future proof.

-- 
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com

Commits

  1. Improve access to parallel query from procedural languages.

  2. plpgsql: Don't generate parallel plans for RETURN QUERY.

  3. Allow for parallel execution whenever ExecutorRun() is done only once.