Re: parallelize queries containing subplans

Amit Kapila <amit.kapila16@gmail.com>

From: Amit Kapila <amit.kapila16@gmail.com>
To: Robert Haas <robertmhaas@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2017-01-16T15:43:15Z
Lists: pgsql-hackers

Attachments

On Thu, Jan 12, 2017 at 7:56 PM, Amit Kapila <amit.kapila16@gmail.com> wrote:
> On Thu, Jan 12, 2017 at 8:51 AM, Robert Haas <robertmhaas@gmail.com> wrote:
>> On Wed, Jan 11, 2017 at 9:58 PM, Amit Kapila <amit.kapila16@gmail.com> wrote:
>>> The other alternative is to remember this information in SubPlan.  We
>>> can retrieve parallel_safe information from best_path and can use it
>>> while generating SubPlan.  The main reason for storing it in the plan
>>> was to avoid explicitly passing parallel_safe information while
>>> generating SubPlan as plan was already available at that time.
>>> However, it seems there are only two places in code (refer
>>> build_subplan) where this information needs to be propagated.  Let me
>>> know if you prefer to remember the parallel_safe information in
>>> SubPlan instead of in Plan or if you have something else in mind?
>>
>> I think we should try doing it in the SubPlan, at least, and see if
>> that comes out more elegant than what you have at the moment.
>>
>
> Okay, done that way.  I have fixed the review comments raised by Dilip
> as well and added the test case in attached patch.
>

After commit-ab1f0c8, this patch needs a rebase.  Attached find
rebased version of the patch.

Thanks to Kuntal for informing me offlist that this patch needs rebase.

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

Commits

  1. Allow parallel workers to execute subplans.