Re: Is update statistics really necessary ?

From: Frederico Cox <fredcox@cpqd.com.br> > >I would like to clarify some questions about rule versus cost query >optmizer in Informix. > >I have Informix On Line Dynamic Server version 7.24. My database has about >300GB of size. I have to apply update statistics to get performance but it >is consuming about 12 hours to finish. This time is becoming critical to >my environment. > >So, I am thinking to use another approach. > >Is it possible to set the optmizer to work by rule (not use cost) ? I >thing that if I use this approach the decision of the optmizer will be >based in predefined rules, so will be not necessary to apply update >statistics, won't it ? > >What I will have to set in my environment to work in this way (only set >OPTCMPIND to 0) ? Hoo-boy, you're barking up the wrong tree here. You can't revert to rule-based optimisers, you can include hints to the optimiser in 7.31. However, the easiest thing to do is to just get Art Kagel's dostats.ec and run that -- problem solved. :-) You might want to change your update statistics to only run frequently on volatile tables, the others can be done weekly or whatever. HTH. ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com