Re: Parallelize correlated subqueries that execute within each worker

From: Zhihong Yu <zyu(at)yugabyte(dot)com>
To: James Coleman <jtc331(at)gmail(dot)com>
Cc: Daniel Gustafsson <daniel(at)yesql(dot)se>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
Subject: Re: Parallelize correlated subqueries that execute within each worker
Date: 2021-09-07 15:06:00
Message-ID: CALNJ-vTpbZtTcJ+Y-kUc5D5_rNr4-1YY=-T2WF+t5425MSuCtQ@mail.gmail.com
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On Tue, Sep 7, 2021 at 6:17 AM James Coleman <jtc331(at)gmail(dot)com> wrote:

> On Wed, Sep 1, 2021 at 7:06 AM Daniel Gustafsson <daniel(at)yesql(dot)se> wrote:
> >
> > > On 7 May 2021, at 18:30, James Coleman <jtc331(at)gmail(dot)com> wrote:
> >
> > > ..here we are now, and I finally have this patch cleaned up
> > > enough to share.
> >
> > This patch no longer applies to HEAD, can you please submit a rebased
> version?
>
> See attached.
>
> Thanks,
> James
>
Hi,
For v2-0002-Parallel-query-support-for-basic-correlated-subqu.patch :

+ * is when we're going to execute multiple partial parths in parallel

parths -> paths

if (index->amcanparallel &&
- rel->consider_parallel && outer_relids == NULL &&
- scantype != ST_BITMAPSCAN)
+ rel->consider_parallel && outer_relids == NULL &&
+ scantype != ST_BITMAPSCAN)

the change above seems unnecessary since the first line of if condition
doesn't change.
Similar comment for the next hunk.

+ * It's not a partial path; it'a a full path that is executed
as a subquery.

it'a a -> it's a

+ /* rel->consider_parallel_rechecking_params = false; */
+ /* rel->partial_pathlist = NIL; */

The commented code can be taken out.

Cheers

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