On Mon, 2006-10-23 at 11:13 -0500, Jim C. Nasby wrote: > On Fri, Oct 20, 2006 at 12:05:43AM -0700, Aaron Stone wrote: > > Ok, I think we should change the query in db_getmailbox_count to be < 2 > > because the plan really is a lot less expensive than IN (0, 1). I know > > this was a thread/bug we had a week or two ago, but it popped into my > > head today that maybe the planner was guessing the IN (0, 1) meant the > > same at < 2. It doesn't, and even on Pg 8, it's still more expensive. > > > > Aaron > > > > dbmail=# explain select message_idnr from dbmail_messages where > > mailbox_idnr = 1 and status in (0, 1) order by message_idnr asc; > > Your results are 100% meaningless, because they do not show how long it > actually took to run the queries. Without the data from EXPLAIN ANALYZE > there is no basis for changing the query.
Do you have such data available? > BTW, if you are going to change it, it would be more clear to do BETWEEN > 0 AND 1, which the optimizer should be able to deal with just as well as > < 2. I am perfectly comfortable making whatever change works best. Do you have data that shows how the BETWEEN is optimized? Aaron
