Repair crash with unsortable grouping sets.
If there were multiple grouping sets, none of them empty, all of which
were unsortable, then an oversight in consider_groupingsets_paths led
to a null pointer dereference. Fix, and add a regression test for this
case.
Per report from Dang Minh Huong, though I didn't use their patch.
Backpatch to 10.x where hashed grouping sets were added.
Branch
------
REL_10_STABLE
Details
-------
https://git.postgresql.org/pg/commitdiff/cf21c46495897cf3a59f2b1230b522a969a17bea
Modified Files
--------------
src/backend/optimizer/plan/planner.c | 23 ++++++++++++++++++++++-
src/test/regress/expected/groupingsets.out | 12 ++++++++++++
src/test/regress/sql/groupingsets.sql | 5 +++++
3 files changed, 39 insertions(+), 1 deletion(-)