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Re: inefficient/wrong plan cache mode selection for queries with partitioned tables (postgresql 17)

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

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Maxim Boguk <maxim.boguk@gmail.com>
Cc: David Rowley <dgrowleyml@gmail.com>, Andrei Lepikhov <lepihov@gmail.com>, Pgsql Performance <pgsql-performance@lists.postgresql.org>
Date: 2025-05-12T15:33:02Z
Lists: pgsql-performance 
Maxim Boguk <maxim.boguk@gmail.com> writes:
> And the problem is that the cost of a custom plan ignores the cost of
> planning itself (which is like 2x orders of magnitude worse than the cost
> of real time partition pruning of a generic plan).

False.  The estimate is evidently pretty wrong, but it's not that
there is no consideration at all.  See around line 1370 in
src/backend/utils/cache/plancache.c.

			regards, tom lane