> -----Original Message-----
> From: majordomo-owner@hub.org [mailto:majordomo-owner@hub.org]On Behalf
> Of Don Baccus
>
> Whatever ... in this particular case - referential integrity
> with MATCH <unspecified> and MATCH PARTIAL and multi-column
> foreign keys - performance will likely drop spectacularly once the
> leading column is NULL, while (say) with Oracle you'd expect much
> less of a performance hit.
>
As for NULL,it seems possible to look up NULL keys in a btree index
because NULL == NULL for btree indexes.
I've wondered why PostgreSQL's planner/executor never looks up
indexes for queries using 'IS NULL'.
Regards.
Hiroshi Inoue
Inoue@tpf.co.jp