On Sun, Jun 11, 2017 at 10:36 AM, Tom Lane <t...@sss.pgh.pa.us> wrote: >> Do you mean teaching the optimizer to do something like this?: > > Uh, no. I don't think we want to add any run-time checks. The point in > this example is that we'd get a better rowcount estimate if we noticed > that the FK constraint could be considered while estimating the size of > the partsupp-to-aggregated-subquery join.
Sorry for not considering the context of the thread more carefully. Robert said something about selectivity estimation and TPC-H to me, which I decide to research; I then rediscovered this thread. Clearly Q20 is designed to reward systems that do better with moving predicates into subqueries, as opposed to systems with better selectivity estimation. -- Peter Geoghegan -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
