Thread: pgsql: Fix UNION/INTERSECT/EXCEPT over no columns.
Fix UNION/INTERSECT/EXCEPT over no columns. Since 9.4, we've allowed the syntax "select union select" and variants of that. However, the planner wasn't expecting a no-column set operation and ended up treating the set operation as if it were UNION ALL. Turns out it's trivial to fix in v10 and later; we just need to be careful about not generating a Sort node with no sort keys. However, since a weird corner case like this is never going to be exercised by developers, we'd better have thorough regression tests if we want to consider it supported. Per report from Victor Yegorov. Discussion: https://postgr.es/m/CAGnEbojGJrRSOgJwNGM7JSJZpVAf8xXcVPbVrGdhbVEHZ-BUMw@mail.gmail.com Branch ------ REL_10_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/c252ccda74295ad292c407a361c9d55ca0554e00 Modified Files -------------- src/backend/optimizer/plan/createplan.c | 1 - src/backend/optimizer/prep/prepunion.c | 26 +++----- src/test/regress/expected/union.out | 115 ++++++++++++++++++++++++++++++++ src/test/regress/sql/union.sql | 43 ++++++++++++ 4 files changed, 168 insertions(+), 17 deletions(-)