From 68740de04e3bb21b15ed239def61474428a79cf4 Mon Sep 17 00:00:00 2001 From: Tomas Vondra Date: Fri, 16 Apr 2021 03:09:48 +0200 Subject: [PATCH 2/2] tweaks --- src/backend/optimizer/path/equivclass.c | 25 ++++++++++++++++++++----- 1 file changed, 20 insertions(+), 5 deletions(-) diff --git a/src/backend/optimizer/path/equivclass.c b/src/backend/optimizer/path/equivclass.c index 27867e16e8..bf1c95c847 100644 --- a/src/backend/optimizer/path/equivclass.c +++ b/src/backend/optimizer/path/equivclass.c @@ -799,6 +799,14 @@ find_em_expr_for_rel(EquivalenceClass *ec, RelOptInfo *rel) return NULL; } +/* + * Checks if node is member of the list. RelabelType is ignored for expressions + * in the list. + * + * XXX We have list_member_XXX for different types, so maybe make that consistent? + * XXX Perhaps explain why the relabel is ignored. Why is it ignored recursively? + * XXX Maybe reference tlist_member_ignore_relabel, which is doing the same thing? + */ static Expr* expr_list_member_ignore_relabel(Expr *node, List *exprlist) { @@ -882,24 +890,31 @@ find_em_expr_usable_for_sorting_rel(PlannerInfo *root, EquivalenceClass *ec, * up a volatile expression to the proper tlist entry, it doesn't seem * valuable here to expend the work trying to find a match in the * target's exprs since such a sort will have to be postponed anyway. + * + * XXX Doesn't this comment need an update? + * + * XXX Maybe we should start matching the tlist entries? After all, + * prepare_sort_from_pathkeys matches directly, and only if not found + * it does the pull_var_clause stuff, no? */ if (ec->ec_has_volatile) return NULL; - + /* XXX comment would be nice ... */ exprvars = pull_var_clause((Node *) em_expr, PVC_INCLUDE_AGGREGATES | PVC_INCLUDE_WINDOWFUNCS | PVC_INCLUDE_PLACEHOLDERS); + + /* All expressions have to be present in the target list. */ foreach(k, exprvars) { if (!expr_list_member_ignore_relabel(lfirst(k), target->exprs)) - break; + return NULL; } - list_free(exprvars); - if (!k) /* If we made it through exprvars finding a tlist member for each */ - return em->em_expr; /* found usable expression */ + /* all the expressions have a matching target entry. */ + return em->em_expr; } /* We didn't find any suitable equivalence class expression */ -- 2.30.2