Re: Distributions

Stefan Weideneder wrote: > > Jay Aymond wrote: [SNIP other stuff] > Do you think it's a good idea to give the optimizer detailled > informations for columns, if the information will not cause > a better query plan ? Don't you believe that it will slow down > those queries that do not benefit from the detailled distributions ? > Be carefull if you start "update statistics medium/high for table xyz". > Only make use of "update statistics high/medium ..." when you are > sure that the optimizer will need this additional information. As the author of dostats.ec I have to disagree with this statement. It cannot hurt to have more information in the distributions it can help the optimizer to make better decisions. Yes, there are bugs in the optimizer and situations where the optimizer does not make the very best decisions and the level of stats for a particular table needs to be reduced, but this is the exception and in general use the recommendations in the release notes for 7.2x, or dostats.ec which implements them, to get the best balance between the quality of the stats and the time needed to produce them. For me it is only the time needed that prevents me from using HIGH for all tables and columns. Art S. Kagel