"Tom Lane" <[EMAIL PROTECTED]> writes: > Gregory Stark <[EMAIL PROTECTED]> writes: >> I imagine you've thought of this already but just in case, the cost of the >> function call has to be combined with the selectivity to get this right. If >> you can do an expensive but very selective clause first and save 100 cheap >> calls that almost always return true it may still be worthwhile. > > I've thought of it, but I haven't figured out a reasonable algorithm for > ordering the clauses in view of that. Have you?
Hum, I hadn't tried. Now that I think about it it's certainly not obvious. And picturing the possible failure modes I would rather it execute cheap expressions more often than necessary than call some user-defined perl function that could be doing i/o or involve waiting on other resources any more than absolutely necessary. So I guess what you originally described is safest. -- Gregory Stark EnterpriseDB http://www.enterprisedb.com ---------------------------(end of broadcast)--------------------------- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
