Remove an unsafe Assert, and explain join_clause_is_movable_into() better.
join_clause_is_movable_into() is approximate, in the sense that it might
sometimes return "false" when actually it would be valid to push the given
join clause down to the specified level. This is okay ... but there was
an Assert in get_joinrel_parampathinfo() that's only safe if the answers
are always exact. Comment out the Assert, and add a bunch of commentary
to clarify what's going on.
Per fuzz testing by Andreas Seltenreich. The added regression test is
a pretty silly query, but it's based on his crasher example.
Back-patch to 9.2 where the faulty logic was introduced.
Branch
------
REL9_2_STABLE
Details
-------
http://git.postgresql.org/pg/commitdiff/d6a8a29ac2bca06d4466e449f13d0cc52220714b
Modified Files
--------------
src/backend/optimizer/util/relnode.c | 9 ++++++
src/backend/optimizer/util/restrictinfo.c | 31 +++++++++++++++----
src/test/regress/expected/join.out | 48 +++++++++++++++++++++++++++++
src/test/regress/sql/join.sql | 27 ++++++++++++++++
4 files changed, 109 insertions(+), 6 deletions(-)