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.
