Re: Update Statistics Low, Medium & High

> >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. > 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: Am I missing something here? Aren't we supposed to be talking about SET OPTIMIZATION {HIGH | LOW}? UPDATE STATISTICS creates (inter alia) data distributions. I don't think itforces the optimiser to do anything with them... SET OPTIMIZATION forces the optimiser to consider every query path or not. Probably wrong again... <sigh> -- Ciao, Billy +------------------------------------------------------------------------------+ | Billy Wheeler Junior Programmer / Director The West Solutions Group | +------------------------------------------------------------------------------+ | (E) billy@west.co.za (U) http://www.west.co.za/billy.html | +------------------------------------------------------------------------------+ | A WAY COMPUTERS CHANGED THE WORLD: 1 million banking errors | +------------------------------------------------------------------------------+