Clean up remove_rel_from_query() after self-join elimination commit The self-join elimination (SJE) commit grafted self-join removal onto remove_rel_from_query(), which was originally written for left-join removal only. This resulted in several issues:
- Comments throughout remove_rel_from_query() still assumed only left-join removal, making the code misleading. - ChangeVarNodesExtended was called on phv->phexpr with subst=-1 during left-join removal, which is pointless and confusing since any surviving PHV shouldn't reference the removed rel. - phinfo->ph_lateral was adjusted for left-join removal, which is unnecessary since the removed relid cannot appear in ph_lateral for outer joins. - The comment about attr_needed reconstruction was in remove_rel_from_query(), but the actual rebuild is performed by the callers. - EquivalenceClass processing in remove_rel_from_query() is redundant for self-join removal, since the caller (remove_self_join_rel) already handles ECs via update_eclasses(). - In remove_self_join_rel(), ChangeVarNodesExtended was called on root->processed_groupClause, which contains SortGroupClause nodes that have no Var nodes to rewrite. The accompanying comment incorrectly mentioned "HAVING clause". This patch fixes all these issues, clarifying the separation between left-join removal and self-join elimination code paths within remove_rel_from_query(). The resulting code is also better structured for adding new types of join removal (such as inner-join removal) in the future. Author: Richard Guo <[email protected]> Reviewed-by: Tender Wang <[email protected]> Reviewed-by: Andrei Lepikhov <[email protected]> Reviewed-by: wenhui qiu <[email protected]> Discussion: https://postgr.es/m/CAMbWs48JC4OVqE=3gmb6se2wmrnnfmyfyyxm-09vgpm+vwe...@mail.gmail.com Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/20efbdffeb6418afa13d6c8457054735d11c7e3a Modified Files -------------- src/backend/optimizer/plan/analyzejoins.c | 453 +++++++++++++++--------------- 1 file changed, 231 insertions(+), 222 deletions(-)
