Re: Update Statistics Low, Medium & High (oops)

At 08:47 AM 8/30/96 -0700, you wrote: >Clem Akins wrote: >> >> >In our system, we discover sometimes some tables in index searching is much >> >faster while we update their statistics low or medium instead of high. >> > >> >We have an idea that update all tables high statistics with reference to the >> >server admin. guide. >> >> I heard a discussion the other day which indicated that when you update >> statistics "high" it causes the optimizer to evaluate every possible query >> path. This evaluation might take longer than the actual query--it depends >> on the indexes and the query. On the "medium" or "low" settings the optimizer >> evaluates only the most likely paths, and chooses one quickly. Though I could >> not find a definitive explanation of this exact point in the documentation, >> a picture might look like: >... > >Clem, > >Have a look at SET OPTIMIZATION LOW|HIGH. I think this is what you are >referring to. Changing the UPDATE STATISTICS doesn't affect the number [...] Oops! That's what I get for quoting an overheard conversation and firing off a reflex answer. That, and a brain cramp about the obvious SET OPTIMIZATION parameter. Sorry, please deduct the price of this advice from my bill. ;) Clem ______________________________________________________ Clem Akins (aka clema@informix.com) Informix Software, Inc (Standard disclaimers apply) International Technical Support Last seen: back in Menlo Park, California