Re: Cost Based Optimizer

In <1993Sep27.130957.8224@pyra.co.uk> graeme@pyra.co.uk (Graeme Sargent) writes: >This is to be expected. OnLine uses a Selectivity Factor of >1/sysindexes.nunique for an indexed_col = <literal> filter and a >Selectivity Factor of 0.2 for a matches expression. I'd be happy to be allowed to write, select * from foo where bar matches "blurfl*" selectivity 1/100000 ... Or even being able to tell it the estimated #rows directly (or better yet,allow either). How 'bout it, Informix? I'd love to tell your optimizer what I know... Imagine, doing "or" wouldn't necessarily do a sequential scan all the time! select * from foo where (key = 1000 selectivity 1/100000 or key in (select groupkey from groups where key = 1000 selectivity 1/10e7) ) and date > 1/1/1990 selectivity 0.2 (Which is, BTW, nearly like some code in our system that must be done with a union else it does a sequential scan on millions of records.) I would gladly give up sql portability for this... -- Andrew Burt aburt@du.edu "But if he was dying he wouldn't bother to carve "Aaaaargh", he'd just say it."