Push scan/join target list beneath Gather when possible. This means that, for example, "SELECT expensive_func(a) FROM bigtab WHERE something" can compute expensive_func(a) in the workers rather than the leader if it happens to be parallel-safe, which figures to be a big win in some practical cases.
Currently, we can only do this if the entire target list is parallel-safe. If we worked harder, we might be able to evaluate parallel-safe targets in the worker and any parallel-restricted targets in the leader, but that would be more complicated, and there aren't that many parallel-restricted functions that people are likely to use in queries anyway. I think. So just do the simple thing for the moment. Robert Haas, Amit Kapila, and Tom Lane Branch ------ master Details ------- http://git.postgresql.org/pg/commitdiff/992b5ba30dcafdc222341505b072a6b009b248a7 Modified Files -------------- src/backend/optimizer/plan/createplan.c | 25 ++++++++++++++----------- src/backend/optimizer/util/pathnode.c | 30 ++++++++++++++++++++++++++++++ 2 files changed, 44 insertions(+), 11 deletions(-) -- Sent via pgsql-committers mailing list (pgsql-committers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-committers
