Christopher Masto <chris+pg-general(at)netmonger(dot)net> writes:
> I guess maybe I'm expecting too much magic optimization.
You're expecting the system to transform
(SELECT foo UNION SELECT bar) WHERE condition
into
(SELECT foo WHERE condition) UNION (SELECT bar WHERE condition)
It's not immediately obvious to me that these are equivalent, or
perhaps I should say it's not clear under what conditions is the
transformation legitimate.
regards, tom lane