Horton

Re: Oversight in reparameterize_path_by_child leading to executor crash

Richard Guo <guofenglinux@gmail.com>

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From: Richard Guo <guofenglinux@gmail.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Andrei Lepikhov <a.lepikhov@postgrespro.ru>, Alena Rybakina <lena.ribackina@yandex.ru>, Tom Lane <tgl@sss.pgh.pa.us>, Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2024-01-17T09:01:36Z
Lists: pgsql-hackers

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Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Postpone reparameterization of paths until create_plan().

  2. Apply band-aid fix for an oversight in reparameterize_path_by_child.

Attachments

On Tue, Jan 16, 2024 at 2:30 AM Robert Haas <robertmhaas@gmail.com> wrote:

> On Mon, Jan 8, 2024 at 3:32 AM Richard Guo <guofenglinux@gmail.com> wrote:
> > Thanks for the suggestion.  Attached is an updated patch which is added
> > with a commit message that tries to explain the problem and the fix.
>
> This is great. The references to "the sampling infos" are a little bit
> confusing to me. I'm not sure if this is referring to
> TableSampleClause objects or what.


Yeah, it's referring to TableSampleClause objects.  I've updated the
commit message to clarify that.  In passing I also updated the test
cases a bit.  Please see
v10-0001-Postpone-reparameterization-of-paths-until-when-creating-plans.patch


> > Fair point.  I think we can back-patch a more minimal fix, as Tom
> > proposed in [1], which disallows the reparameterization if the path
> > contains sampling info that references the outer rel.  But I think we
> > need also to disallow the reparameterization of a path if it contains
> > restriction clauses that reference the outer rel, as such paths have
> > been found to cause incorrect results, or planning errors as in [2].
>
> Do you want to produce a patch for that, to go along with this patch for
> master?


Sure, here it is:
v10-0001-Avoid-reparameterizing-Paths-when-it-s-not-suitable.patch

Thanks
Richard