Re: parallelize queries containing subplans

Robert Haas <robertmhaas@gmail.com>

From: Robert Haas <robertmhaas@gmail.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2017-01-12T03:21:46Z
Lists: pgsql-hackers
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.

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


Commits

  1. Allow parallel workers to execute subplans.