| From: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> |
|---|---|
| To: | Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Kevin Grittner <kgrittn(at)ymail(dot)com>, David Rowley <dgrowleyml(at)gmail(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>, Kouhei Kaigai <kaigai(at)ak(dot)jp(dot)nec(dot)com>, Amit Langote <amitlangote09(at)gmail(dot)com>, Fabrízio Mello <fabriziomello(at)gmail(dot)com>, Thom Brown <thom(at)linux(dot)com>, Stephen Frost <sfrost(at)snowman(dot)net>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Parallel Seq Scan |
| Date: | 2015-04-21 11:57:48 |
| Message-ID: | CAA4eK1+U+93No884CGF_gBjNdHw0K=Zqr2O-0bxZ2Tcjdx4Rqw@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, Apr 21, 2015 at 6:34 AM, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp
> wrote:
> On 2015-04-21 AM 03:29, Robert Haas wrote:
> > On Wed, Apr 8, 2015 at 3:38 AM, Amit Langote wrote:
> >> On 08-04-2015 PM 12:46, Amit Kapila wrote:
> >>> Going forward, I think we can improve the same if we decide not to
shutdown
> >>> parallel workers till postmaster shutdown once they are started and
> >>> then just allocate them during executor-start phase.
> >>
> >> I wonder if it makes sense to invent the notion of a global pool of
workers
> >> with configurable number of workers that are created at postmaster
start and
> >> destroyed at shutdown and requested for use when a query uses
parallelizable
> >> nodes.
> >
> > Short answer: Yes, but not for the first version of this feature.
> >
>
> Agreed.
>
> Perhaps, Amit has worked (is working) on "reuse the same workers for
> subsequent operations within the same query"
>
What I am planning to do is Destroy the resources (parallel context) once
we have fetched all the tuples from Funnel node, so that we don't block
all resources till end of execution. We can't say that as reuse rather it
will allow multiple nodes in same statement to use workers when there
is a restriction on total number of workers (max_worker_processed) that
can be used.
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com
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