Re: Performance With 7.21 and HSTools

Pascal PIZEINE wrote: > > We are using for our developments the following configuration : [SNIP] > Since we have upgraded informix 7.10 to 7.21, we have performance problems. > Some queries do not use index but sequential scan. This problem occurs only > with index on CHAR type and it depends on the query writing (see samples > below). It seems to be an informix problem but we are not sure. > We have tried UPDATE STATISTICS then dbexport/dbimport our database; i Sorry but this just looks like no data distributions are available. You state that you updated statistics, how, what command. If you only did "UPDATE STATISTICS FOR TABLE inscri;" you did not create data distributions. Execute the following commands: UPDATE STATISTICS low FOR TABLE inscri; UPDATE STATISTICS medium FOR TABLE inscri(idrubric) DISTRIBUTIONS ONLY; UPDATE STATISTICS high FOR TABLE inscri(indinscri); If this does not work I suggest you create the following index making every search KEY-ONLY (do not forget the unique as it creates a more efficient index when the keys are indeed unique): create unique index inscri_ix1 on inscri(idinscri,idrubric); Art S. Kagel