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Re: BUG #19449: Massive performance degradation for complex query on Postgres 16+ (few seconds -> multiple hours)

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Tomas Vondra <tomas@vondra.me>
Cc: Adrian Mönnich <adrian.moennich@cern.ch>, Andres Freund <andres@anarazel.de>, pgsql-bugs@lists.postgresql.org, Tomas Vondra <tv@fuzzy.cz>, Thomas Munro <thomas.munro@gmail.com>
Date: 2026-04-02T22:43:36Z
Lists: pgsql-bugs 
Tomas Vondra <tomas@vondra.me> writes:
> An interesting question is "What changed in PG16?" causing the query to
> fail, when it worked OK on earlier versions.

"git bisect" could be informative here.  I agree with trying to
minimize the query first, though --- else you may waste time
going down blind alleys, as a result of planner changes changing
the join order without affecting the critical executor behavior.

			regards, tom lane

Commits

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

  1. Improve hash join's handling of tuples with null join keys.

  2. Parallel Hash Full Join.