From 07746a8ef2a871d904c26364cdca4e7feeffe395 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Mon, 6 May 2024 14:22:45 -0400 Subject: [PATCH] Finish incomplete revert of ec63622c0. The code change this made might well be fine to keep, but the comment justifying it by reference to self-join removal isn't. Let's just go back to the status quo ante, pending a more thorough review/redesign of SJE. (I found this by grepping to see if any references to self-join removal remained in the tree.) --- src/backend/optimizer/prep/prepunion.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c index 3f14e90a45..30068c27a1 100644 --- a/src/backend/optimizer/prep/prepunion.c +++ b/src/backend/optimizer/prep/prepunion.c @@ -662,17 +662,14 @@ build_setop_child_paths(PlannerInfo *root, RelOptInfo *rel, * otherwise do statistical estimation. * * XXX you don't really want to know about this: we do the estimation - * using the subroot->parse's original targetlist expressions, not the + * using the subquery's original targetlist expressions, not the * subroot->processed_tlist which might seem more appropriate. The reason * is that if the subquery is itself a setop, it may return a * processed_tlist containing "varno 0" Vars generated by * generate_append_tlist, and those would confuse estimate_num_groups * mightily. We ought to get rid of the "varno 0" hack, but that requires * a redesign of the parsetree representation of setops, so that there can - * be an RTE corresponding to each setop's output. Note, we use this not - * subquery's targetlist but subroot->parse's targetlist, because it was - * revised by self-join removal. subquery's targetlist might contain the - * references to the removed relids. + * be an RTE corresponding to each setop's output. */ if (pNumGroups) { @@ -685,7 +682,7 @@ build_setop_child_paths(PlannerInfo *root, RelOptInfo *rel, *pNumGroups = rel->cheapest_total_path->rows; else *pNumGroups = estimate_num_groups(subroot, - get_tlist_exprs(subroot->parse->targetList, false), + get_tlist_exprs(subquery->targetList, false), rel->cheapest_total_path->rows, NULL, NULL);