From: Tom Lane Date: Thu, 10 Nov 2016 16:31:56 +0000 (-0500) Subject: Fix partial aggregation for the case of a degenerate GROUP BY clause. X-Git-Tag: REL_10_BETA1~1419 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=e1b449bea909fa70211841d508cfaf91d18a6abb;p=postgresql Fix partial aggregation for the case of a degenerate GROUP BY clause. The plan generated for sorted partial aggregation with "GROUP BY constant" included a Sort node with no sort keys, which the executor does not like. Per report from Steve Randall. I'd add a regression test case if I could think of a compact one, but it doesn't seem worth expending lots of cycles on. Report: --- diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c index 644b8b6763..d8c5dd34d6 100644 --- a/src/backend/optimizer/plan/planner.c +++ b/src/backend/optimizer/plan/planner.c @@ -3741,11 +3741,11 @@ create_grouping_paths(PlannerInfo *root, &total_groups); /* - * Gather is always unsorted, so we'll need to sort, unless - * there's no GROUP BY clause, in which case there will only be a - * single group. + * Since Gather's output is always unsorted, we'll need to sort, + * unless there's no GROUP BY clause or a degenerate (constant) + * one, in which case there will only be a single group. */ - if (parse->groupClause) + if (root->group_pathkeys) path = (Path *) create_sort_path(root, grouped_rel, path,