Horton

Fix asymmetry in setting EquivalenceClass.ec_sortref

Alexander Korotkov <akorotkov@postgresql.org>

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Commit: 199012a3d844c6283e0ab4b1139440840a91433d
Author: Alexander Korotkov <akorotkov@postgresql.org>
Date: 2024-06-06T10:41:34Z
Releases: 17.0 
Fix asymmetry in setting EquivalenceClass.ec_sortref

0452b461bc made get_eclass_for_sort_expr() always set
EquivalenceClass.ec_sortref if it's not done yet.  This leads to an asymmetric
situation when whoever first looks for the EquivalenceClass sets the
ec_sortref.  It is also counterintuitive that get_eclass_for_sort_expr()
performs modification of data structures.

This commit makes make_pathkeys_for_sortclauses_extended() responsible for
setting EquivalenceClass.ec_sortref.  Now we set the
EquivalenceClass.ec_sortref's needed to explore alternative GROUP BY ordering
specifically during building pathkeys by the list of grouping clauses.

Discussion: https://postgr.es/m/17037754-f187-4138-8285-0e2bfebd0dea%40postgrespro.ru
Reported-by: Tom Lane
Author: Andrei Lepikhov
Reviewed-by: Alexander Korotkov, Pavel Borisov

Files

PathChange+/−
src/backend/optimizer/path/equivclass.c modified +1 −12
src/backend/optimizer/path/pathkeys.c modified +16 −2
src/backend/optimizer/plan/planner.c modified +12 −4
src/include/optimizer/paths.h modified +2 −1
src/test/regress/expected/aggregates.out modified +47 −0
src/test/regress/sql/aggregates.sql modified +14 −0

Discussion