Tom Lane <tgl@sss.pgh.pa.us> writes:
> But this all looks like a pretty substantial amount of work, and
> given the low level of user demand for improving the performance of
> set operations, it seems to belong fairly far down the to-do list.
Whatever you say, that's your own todo list after all. I just wanted to
chime in and say that it could well be a chicken-and-eggs problem.
Other than that, the only general way I know of to optimise a WHERE
clause containing OR branches is producing the UNION ALL equivalent.
Now maybe I'm all wet, but your explaining sounded like a very nice
first step towards such an automatic optimisation.
Regards,
--
Dimitri Fontaine
http://2ndQuadrant.fr PostgreSQL : Expertise, Formation et Support