pgsql: Fix pull_varnos' miscomputation of relids set for a PlaceHolderV
От | Tom Lane |
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Тема | pgsql: Fix pull_varnos' miscomputation of relids set for a PlaceHolderV |
Дата | |
Msg-id | E1l2gi7-00052j-Gx@gemulon.postgresql.org обсуждение исходный текст |
Список | pgsql-committers |
Fix pull_varnos' miscomputation of relids set for a PlaceHolderVar. Previously, pull_varnos() took the relids of a PlaceHolderVar as being equal to the relids in its contents, but that fails to account for the possibility that we have to postpone evaluation of the PHV due to outer joins. This could result in a malformed plan. The known cases end up triggering the "failed to assign all NestLoopParams to plan nodes" sanity check in createplan.c, but other symptoms may be possible. The right value to use is the join level we actually intend to evaluate the PHV at. We can get that from the ph_eval_at field of the associated PlaceHolderInfo. However, there are some places that call pull_varnos() before the PlaceHolderInfos have been created; in that case, fall back to the conservative assumption that the PHV will be evaluated at its syntactic level. (In principle this might result in missing some legal optimization, but I'm not aware of any cases where it's an issue in practice.) Things are also a bit ticklish for calls occurring during deconstruct_jointree(), but AFAICS the ph_eval_at fields should have reached their final values by the time we need them. The main problem in making this work is that pull_varnos() has no way to get at the PlaceHolderInfos. We can fix that easily, if a bit tediously, in HEAD by passing it the planner "root" pointer. In the back branches that'd cause an unacceptable API/ABI break for extensions, so leave the existing entry points alone and add new ones with the additional parameter. (If an old entry point is called and encounters a PHV, it'll fall back to using the syntactic level, again possibly missing some valid optimization.) Back-patch to v12. The computation is surely also wrong before that, but it appears that we cannot reach a bad plan thanks to join order restrictions imposed on the subquery that the PlaceHolderVar came from. The error only became reachable when commit 4be058fe9 allowed trivial subqueries to be collapsed out completely, eliminating their join order restrictions. Per report from Stephan Springl. Discussion: https://postgr.es/m/171041.1610849523@sss.pgh.pa.us Branch ------ REL_12_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/1cce024fd26be40412c41e9ec59f389cf5979da2 Modified Files -------------- contrib/postgres_fdw/postgres_fdw.c | 6 ++- src/backend/optimizer/path/clausesel.c | 15 +++--- src/backend/optimizer/path/equivclass.c | 21 ++++++--- src/backend/optimizer/path/indxpath.c | 71 +++++++++++++++++++--------- src/backend/optimizer/path/pathkeys.c | 2 +- src/backend/optimizer/path/tidpath.c | 21 +++++---- src/backend/optimizer/plan/analyzejoins.c | 5 +- src/backend/optimizer/plan/initsplan.c | 30 +++++++----- src/backend/optimizer/plan/subselect.c | 7 ++- src/backend/optimizer/prep/prepjointree.c | 44 ++++++++++++------ src/backend/optimizer/util/clauses.c | 11 ++++- src/backend/optimizer/util/inherit.c | 8 +++- src/backend/optimizer/util/orclauses.c | 6 ++- src/backend/optimizer/util/placeholder.c | 5 +- src/backend/optimizer/util/restrictinfo.c | 61 ++++++++++++++++++------ src/backend/optimizer/util/var.c | 77 +++++++++++++++++++++++-------- src/backend/utils/adt/selfuncs.c | 8 +++- src/include/optimizer/clauses.h | 1 + src/include/optimizer/optimizer.h | 4 ++ src/include/optimizer/paths.h | 3 +- src/include/optimizer/planmain.h | 3 +- src/include/optimizer/restrictinfo.h | 9 ++++ src/test/regress/expected/join.out | 36 +++++++++++++++ src/test/regress/sql/join.sql | 16 +++++++ 24 files changed, 354 insertions(+), 116 deletions(-)
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