On Sat, Mar 10, 2012 at 4:16 AM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Robert Haas <robertmh...@gmail.com> writes: >> On Fri, Mar 9, 2012 at 8:15 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: >>> Um ... how do you get the subquery result rows to join to only the >>> correct rows of the other tables? This looks like an unconstrained join >>> to me, which is not what I believe the SQL spec for LATERAL to be, and >>> it doesn't seem especially useful either. (If a subquery could do what >>> people wanted, we'd not be hearing all the requests for LATERAL.) > >> I think LATERAL is intended as more or less an unconstrained nested >> loop with the lateral expression on the inner side, parameterized by >> value from the outer side. Typically it's a SRF. > > Um ... if it's parameterized by values from a "current row" of the outer > side, then it's not an unconstrained join. That would be like doing an > inner indexscan join and producing a cross-join result.
True. I just meant that no join filter was implied. -- 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
