Fix preprocessing of PHV copies pushed down into subqueries Commit e28cf96e9 preprocessed the copies of a query level's PlaceHolderVars that were pushed down into its subqueries in a single walk at the start of subquery_planner. That was wrong in two ways.
First, such copies can also be inserted later, when a join alias Var of the outer level is expanded within a LATERAL subquery or a SubLink's subselect and the alias expression contains a PHV. Those copies were never preprocessed, so a SubLink within them survived into the subquery's lateral references or into a SubPlan's argument list, tripping an assertion in identify_current_nestloop_params or failing in cost_qual_eval. Second, when a pushed-down copy directly contains another PHV of the same level, the walk preprocessed the inner one first and then the outer one, so the outer one's preprocessing ran into the SubPlans just created in the inner one and tripped an assertion in flatten_join_alias_vars. To fix, preprocess the copies right after join alias expansion instead: within preprocess_expression, just before SubLinks are turned into SubPlans, and for LATERAL subquery RTEs, right after their aliases are flattened. Preprocessing a copy handles everything within it, including any further copies nested inside its SubLinks, so the walker no longer looks inside a copy. Back-patch to v16, as with commit e28cf96e9. Reported-by: Fujii Masao <[email protected]> Author: Richard Guo <[email protected]> Discussion: https://postgr.es/m/CAHGQGwH-acRnAk1=Ki4EiAJEt67+Rz=_jyg7pbp_c6bk4oh...@mail.gmail.com Backpatch-through: 16 Branch ------ REL_19_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/22a8f53397ee6d70d8da01bef6835b5843a90df8 Modified Files -------------- src/backend/optimizer/plan/planner.c | 52 ++++++----- src/backend/optimizer/plan/subselect.c | 7 +- src/backend/optimizer/util/var.c | 9 +- src/test/regress/expected/join.out | 154 ++++++++++++++++++++++++++++++--- src/test/regress/sql/join.sql | 35 ++++++++ 5 files changed, 216 insertions(+), 41 deletions(-)
