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Re: postgres_fdw: wrong results with self join + enable_nestloop off

Etsuro Fujita <etsuro.fujita@gmail.com>

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From: Etsuro Fujita <etsuro.fujita@gmail.com>
To: Nishant Sharma <nishant.sharma@enterprisedb.com>
Cc: Suraj Kharage <suraj.kharage@enterprisedb.com>, Richard Guo <guofenglinux@gmail.com>, pgsql-hackers@postgresql.org
Date: 2023-06-14T06:49:37Z
Lists: pgsql-hackers

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On Mon, Jun 5, 2023 at 10:19 PM Etsuro Fujita <etsuro.fujita@gmail.com> wrote:
> To avoid this issue, I am wondering if we should modify
> add_paths_to_joinrel() in back branches so that it just disallows the
> FDW to consider pushing down joins when the restrictlist has
> pseudoconstant clauses.  Attached is a patch for that.

I think that custom scans have the same issue, so I modified the patch
further so that it also disallows custom-scan providers to consider
join pushdown in add_paths_to_joinrel() if necessary.  Attached is a
new version of the patch.

Best regards,
Etsuro Fujita

Commits

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

  1. Re-allow FDWs and custom scan providers to replace joins with pseudoconstant quals.

  2. Disallow replacing joins with scans in problematic cases.

  3. doc: PQinitOpenSSL and PQinitSSL are obsolete in OpenSSL 1.1.0+