Older versions of PG were inefficient with larger numbers of elements in an
IN query, and in fact would error out with something about lack of stack
space if you used very many (a few hundred IIRC).
8.x something was supposed to have improved that. Using 8.3 recently, after
an "oopsie" with some development data, I inadvertently confirmed that it
works and performance is not too bad with >34,000 items in an IN clause ;-)
--
Scott Ribe
scott_ribe(at)killerbytes(dot)com
http://www.killerbytes.com/
(303) 722-0567 voice