Re: parallelize queries containing initplans

From: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>, Kuntal Ghosh <kuntalghosh(dot)2007(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: parallelize queries containing initplans
Date: 2017-11-03 13:00:15
Message-ID: CAA4eK1L+UnZa5KiiU3VXGhfpgc3DjyuEz30A12nyMoxD1nG48g@mail.gmail.com
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On Mon, Oct 30, 2017 at 10:07 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Mon, Oct 30, 2017 at 9:00 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>> Now that the PARAM_EXTERN issue is fixed, I have rebased this patch.
>> This patch had been switched to Ready For Committer in last CF, then
>> Robert had comments which I have addressed, so I think the status
>> should be switched back to Ready For committer. Let me know if you
>> think it should be switched to some other status.
>
> The change to ExplainPrintPlan doesn't look good to me, because it
> actually moves the initPlan; I don't think it's good for EXPLAIN to
> mutate the plan state tree. It should find a way to display the
> results *as if* the initPlans were attached to the subnode, but
> without actually moving them.
>

Actually, with the latest patch, we don't need these changes in
ExplainPrintPlan. Earlier, we need these changes because the patch
had changed SS_charge_for_initplans to mark the path with initplan as
parallel safe. However, after removing that change in the previous
version of patch [1], this is not required as now we won't add gather
on top plan node having initplan.

[1] - https://www.postgresql.org/message-id/CAA4eK1JD%3DpJYBn8rN5RimiEVtPJmVNmyq5p6VoZBnUw2xRYB7w%40mail.gmail.com
--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com

Attachment Content-Type Size
pq_pushdown_initplan_v14.patch application/octet-stream 30.7 KB

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