| From: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> |
|---|---|
| To: | "Hou, Zhijie" <houzj(dot)fnst(at)cn(dot)fujitsu(dot)com> |
| Cc: | Greg Nancarrow <gregn4422(at)gmail(dot)com>, vignesh C <vignesh21(at)gmail(dot)com>, Bharath Rupireddy <bharath(dot)rupireddyforpostgres(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Dilip Kumar <dilipbalaut(at)gmail(dot)com> |
| Subject: | Re: Parallel INSERT (INTO ... SELECT ...) |
| Date: | 2020-12-23 02:47:20 |
| Message-ID: | CAA4eK1LMmz58ej5BgVLJ8VsUGd=+KcaA8X=kStORhxpfpODOxg@mail.gmail.com |
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On Wed, Dec 23, 2020 at 7:52 AM Hou, Zhijie <houzj(dot)fnst(at)cn(dot)fujitsu(dot)com> wrote:
>
> Hi
>
> > > I may be wrong, and if I miss sth in previous mails, please give me some
> > hints.
> > > IMO, serial insertion with underlying parallel SELECT can be
> > > considered for foreign table or temporary table, as the insertions only
> > happened in the leader process.
> > >
> >
> > I don't think we support parallel scan for temporary tables. Can you please
> > try once both of these operations without Insert being involved? If you
> > are able to produce a parallel plan without Insert then we can see why it
> > is not supported with Insert.
>
> Sorry, may be I did not express it clearly, I actually means the case when insert's target(not in select part) table is temporary.
> And you are right that parallel select is not enabled when temporary table is in select part.
>
I think Select can be parallel for this case and we should support this case.
--
With Regards,
Amit Kapila.
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