On Fri, 27 Mar 2009, Marc Mamin wrote:
if your data are mostly static and you have a few mains objects, maybe you can have some gain while defining conditional indexes for those plus one for the rest and then slicing the query:
Maybe. I thought about doing that. However, I am not convinced that would be much of a gain, and would require major rewriting of the queries, as you suggest.
WHERE (l2.start BETWEEN l1.start AND l1.end OR l1.start BETWEEN l2.start AND l2.end )
Yes, that's another way to calculate an overlap. However, it turns out to not be that fast. The problem is that OR there, which causes a bitmap index scan, as the leaf of a nested loop join, which can be rather slow.
Matthew -- I'd try being be a pessimist, but it probably wouldn't work anyway. -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
