On Wed, Apr 26, 2017 at 12:41 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Robert Haas <robertmh...@gmail.com> writes: >> So this is about a cross-type join, >> not multiple types within a single partitioning hierarchy, as you >> might also gather from the subject line of this thread. > > OK, but I still don't understand why any type conversion is needed > in such a case. The existing join estimators don't try to do that, > for the good and sufficient reasons you and I have already mentioned. > They just apply the given cross-type join operator, and whatever > cross-type selectivity estimator might be associated with it, and > possibly other cross-type operators obtained from the same btree > opfamily. > > The minute you get into trying to do any type conversion that is not > mandated by the semantics of the query as written, you're going to > have problems.
There is no daylight whatsoever between us on this issue. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
