Teach planner to account for HAVING quals in aggregation plan nodes. For some reason, we have never accounted for either the evaluation cost or the selectivity of filter conditions attached to Agg and Group nodes (which, in practice, are always conditions from a HAVING clause).
Applying our regular selectivity logic to post-grouping conditions is a bit bogus, but it's surely better than taking the selectivity as 1.0. Perhaps someday the extended-statistics mechanism can be taught to provide statistics that would help us in getting non-default estimates here. Per a gripe from Benjamin Coutu. This is surely a bug fix, but I'm hesitant to back-patch because of the prospect of destabilizing existing plan choices. Given that it took us this long to notice the bug, it's probably not hurting too many people in the field. Discussion: https://postgr.es/m/20968.1509486...@sss.pgh.pa.us Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/7b6c07547190f056b0464098bb5a2247129d7aa2 Modified Files -------------- src/backend/optimizer/path/costsize.c | 46 +++++++++++++++++++++++++++++++++- src/backend/optimizer/prep/prepunion.c | 2 ++ src/backend/optimizer/util/pathnode.c | 25 ++++++++++++++++++ src/include/optimizer/cost.h | 2 ++ 4 files changed, 74 insertions(+), 1 deletion(-) -- Sent via pgsql-committers mailing list (pgsql-committers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-committers
