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

Richard Guo <guofenglinux@gmail.com>

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From: Richard Guo <guofenglinux@gmail.com>
To: Nishant Sharma <nishant.sharma@enterprisedb.com>
Cc: Suraj Kharage <suraj.kharage@enterprisedb.com>, Etsuro Fujita <etsuro.fujita@gmail.com>, pgsql-hackers@postgresql.org
Date: 2023-06-05T03:09:12Z
Lists: pgsql-hackers 
On Fri, Jun 2, 2023 at 8:31 PM Nishant Sharma <
nishant.sharma@enterprisedb.com> wrote:

> *I only had a minor comment on below change:-*
>
>
>
>
>
> *-   gating_clauses = get_gating_quals(root, scan_clauses);+   if
> (best_path->pathtype == T_ForeignScan && IS_JOIN_REL(rel))+
> gating_clauses = get_gating_quals(root, ((ForeignPath *)
> best_path)->joinrestrictinfo);+   else+       gating_clauses =
> get_gating_quals(root, scan_clauses);*
>
> Instead of using 'if' and creating a special case here can't we do
> something in the above switch?
>

I thought about that too.  IIRC I did not do it in that way because
postgresGetForeignPlan expects that there is no scan_clauses for a join
rel.  So doing that would trigger the Assert there.

   /*
    * For a join rel, baserestrictinfo is NIL and we are not considering
    * parameterization right now, so there should be no scan_clauses for
    * a joinrel or an upper rel either.
    */
   Assert(!scan_clauses);

Thanks
Richard

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+