"Jim 'Decibel!' Nasby" <jnasby@xxxxxxxxxxxxxx> writes: > So here's something odd... in both 8.3 and HEAD from a while ago it > gives a better plan for SELECT * than for SELECT count(*): The short answer is that the Subquery Scan nodes can be dropped out when they are no-ops, which is to say producing the same set of columns their input produces (and not testing any filter conditions, but that's not relevant here). SELECT count(*) doesn't want to know about any columns so the output of the UNION arm doesn't match ... regards, tom lane -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
