Re: when to 'update statistics' ???

David Williams wrote: > > In article <5cpsh1$fmr@cssun.mathcs.emory.edu>, Leo_Chen@usc.com.tw > writes > > > > > > > > > > > >Hi all: > > if anyone knows when to do the 'update statistics' ? > > Or, if there is any information (some ratios, for example) indicates > >that the engine needs 'update statistics'?? > > > >leo > > > > > > When users complain the system is getting slow ? > > Seriously most sites I know of run it overnight as well as > bcheck's/tbcheck's to make sure the database is consistent. > > On a very large site you make have to break it up and > update statistics for a few tables day of the week.> > -- > David Williams I agree with both the previous posts. When I initially learned Informix we did it nightly, it was not too time consuming (although newer versions probably do more than that version did), and I could not believe that the next company I worked for only did it when there was a problem (I suspect this is related to why they bounced paychecks and were sued by their customers...and why I got the hell out of there as soon as I could (before my contract was up)) Unless there are conflicts with performance and/or general usage, you should run this stuff (bcheck and UPDATE STATS) as often as possible! bcheck caught problems very often (and there were data problems in older versions of Informix....they seem rarer now, but don't trust any version)