Fix planning of parameterized appendrel paths with expensive join quals. The code in set_append_rel_pathlist() for building parameterized paths for append relations (inheritance and UNION ALL combinations) supposed that the cheapest regular path for a child relation would still be cheapest when reparameterized. Which might not be the case, particularly if the added join conditions are expensive to compute, as in a recent example from Jeff Janes. Fix it to compare child path costs *after* reparameterizing. We can short-circuit that if the cheapest pre-existing path is already parameterized correctly, which seems likely to be true often enough to be worth checking for.
Back-patch to 9.2 where parameterized paths were introduced. Branch ------ REL9_3_STABLE Details ------- http://git.postgresql.org/pg/commitdiff/8b6191e1d5e48d521c42d5f6bdbf8413874f7206 Modified Files -------------- src/backend/optimizer/path/allpaths.c | 104 +++++++++++++++++++++++++++------ src/test/regress/expected/union.out | 34 +++++++++++ src/test/regress/sql/union.sql | 21 +++++++ 3 files changed, 140 insertions(+), 19 deletions(-) -- Sent via pgsql-committers mailing list ([email protected]) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-committers
