Fix planner failure in some cases of sorting by an aggregate. An oversight introduced by the incremental-sort patches caused "could not find pathkey item to sort" errors in some situations where a sort key involves an aggregate or window function.
The basic problem here is that find_em_expr_usable_for_sorting_rel isn't properly modeling what prepare_sort_from_pathkeys will do later. Rather than hoping we can keep those functions in sync, let's refactor so that they actually share the code for identifying a suitable sort expression. With this refactoring, tlist.c's tlist_member_ignore_relabel is unused. I removed it in HEAD but left it in place in v13, in case any extensions are using it. Per report from Luc Vlaming. Back-patch to v13 where the problem arose. James Coleman and Tom Lane Discussion: https://postgr.es/m/91f3ec99-85a4-fa55-ea74-33f85a5c6...@swarm64.com Branch ------ REL_13_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/7bfba4f1933003716d432d29d4d228bcf28e2e70 Modified Files -------------- src/backend/optimizer/path/equivclass.c | 255 ++++++++++++++++++++----- src/backend/optimizer/plan/createplan.c | 118 +----------- src/include/optimizer/paths.h | 8 + src/test/regress/expected/incremental_sort.out | 26 +++ src/test/regress/sql/incremental_sort.sql | 7 + 5 files changed, 262 insertions(+), 152 deletions(-)
