On Feb 7, 2006, at 23:04 , David W wrote:
do i have to prefered to use UNION and INTERSECT or is it better with OR and AND ?
In general, EXPLAIN ANALYZE is your friend. I suspect using OR will be better (and that's only a suspicion), but by using EXPLAIN ANALYZE you can see exactly how the server is planning the queries based on your actual situation (as long as your statistics are accurate. See ANALYZE as well).
[EXPLAIN](http://www.postgresql.org/docs/current/interactive/sql- explain.html) [ANALYZE](http://www.postgresql.org/docs/current/interactive/sql- analyze.html)
Once you've got some good EXPLAIN ANALYZE output, people on the performance list may be able to help out if you still have questions.
http://archives.postgresql.org/pgsql-performance/ Michael Glaesemann grzm myrealbox com
