Tom Lane wrote: > Alvaro Herrera <[EMAIL PROTECTED]> writes: > > I note that the rowcount is not altered by the one-time filter. Is this > > an issue? I imagine the problem is not being able to estimate the > > number of rows that pass the filter. > > That's intentional. The filter is either going to pass all or none of > the rows, not some fraction of them. It clearly isn't very reasonable > to guess that it will pass none of them (except if the qual is actually > constant FALSE). > > > I also wonder whether it wouldn't be better in this case to apply each > > filter to each arm of the merge join. > > Uh, why? For the most part, I'd think the higher you can put the filter > in the plan tree, the better.
Huh, sorry, I had misunderstood the meaning of a _one_-time filter :-) -- Alvaro Herrera http://www.CommandPrompt.com/ PostgreSQL Replication, Consulting, Custom Development, 24x7 support ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org
