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Fix partial aggregation for the case of a degenerate GROUP BY clause.

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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: <CABVd52UAdGXpg_rCk46egpNKYdXOzCjuJ1zG26E2xBe_8bj+Fg@mail.gmail.com>
This commit is contained in:
Tom Lane 2016-11-10 11:31:56 -05:00
parent 0b1b5033ac
commit e1b449bea9
1 changed files with 4 additions and 4 deletions
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8
src/backend/optimizer/plan/planner.c
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@ -3741,11 +3741,11 @@ create_grouping_paths(PlannerInfo *root,
&total_groups); &total_groups);
/* /*
* Gather is always unsorted, so we'll need to sort, unless * Since Gather's output is always unsorted, we'll need to sort,
* there's no GROUP BY clause, in which case there will only be a * unless there's no GROUP BY clause or a degenerate (constant)
* single group. * one, in which case there will only be a single group.
*/ */
if (parse->groupClause) if (root->group_pathkeys)
path = (Path *) create_sort_path(root, path = (Path *) create_sort_path(root,
grouped_rel, grouped_rel,
path, path,