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. regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers