On Fri, 2006-10-20 at 12:27 -0400, Tom Lane wrote: > > This was a direct port from a big fat table. I agree, I'm not > convinced that > > the partial indexes will buy me much, but this box is so IO bound > that the > > planner overhead my just offset the needing to IO bigger indexes. > > Well, you should measure it, but I bet the planner wastes way more > time > considering the twenty-some indexes than is saved by avoiding one > level > of btree search, which is about the most you could hope for.
I note that in allpaths.c:set_plain_rel_pathlist() we consider partial indexes before we consider constraint exclusion. We normally wouldn't notice that but, in this case, that would be a big loss. Is there a reason for that? check_partial_indexes() doesn't seem to have important side-effects that are required for testing whether relation_excluded_by_constraints() -- Simon Riggs EnterpriseDB http://www.enterprisedb.com ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
