On Wed, Apr 26, 2017 at 8:46 PM, Bruce Momjian <br...@momjian.us> wrote:
> On Wed, Apr 26, 2017 at 07:38:05PM +0530, Amit Kapila wrote:
>> >> I have already mentioned the commit id (5e6d8d2b).  Text can be "Allow
>> >> queries containing subplans to execute in parallel".  We should also
>> >> mention in some way that this applies only when the query contains
>> >> uncorrelated subplan.
>> >
>> > Sorry but I don't know what that means, and if I don't know, others
>> > might not either.
>> >
>>
>> regression=# explain (costs off) select count(*) from tenk1 where
>> (two, four) not in     (select hundred, thousand from tenk2 where
>> thousand > 100);
>>                       QUERY PLAN
>> ------------------------------------------------------
>>  Finalize Aggregate
>>    ->  Gather
>>          Workers Planned: 2
>>          ->  Partial Aggregate
>>                ->  Parallel Seq Scan on tenk1
>>                      Filter: (NOT (hashed SubPlan 1))
>>                      SubPlan 1
>>                        ->  Seq Scan on tenk2
>>                              Filter: (thousand > 100)
>> (9 rows)
>>
>
> Oh, so non-correlated subqueries can be run in parallel.  Yes, that is
> something we should have in the release notes.  How is this?
>
>         Author: Robert Haas <rh...@postgresql.org>
>         2017-02-14 [5e6d8d2bb] Allow parallel workers to execute subplans.
>
>         Allow non-correlated subqueries to be run in parallel (Amit Kapila)
>

Looks good to me.


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


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