"Chris Mayfield" <cmayfiel@xxxxxxxxxxxxx> writes: > You may already have this rough idea somewhere, but it seems to me that the > view could be flattened into the upper query as long as the join predicates > don't depend on coalesced columns. In the examples I sent, even if the > COALESCE is evaluated at the very end of the query, the merge join (on the id > columns) would still be correct. I don't remember the example but that's not true in general, consider something like select * from a left outer join ( select *, coalesce(b.x,'foo') from b ) as b using (a.y=b.y) The coalesce() doesn't depend on any join predicates, but if it's evaluated late it will be 'foo' for all the non-matching records instead of NULL. -- Gregory Stark EnterpriseDB http://www.enterprisedb.com Ask me about EnterpriseDB's 24x7 Postgres support! -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
