Optimizer misbehaving

We are experiencing some "very strange" behavior with our optimizer. We are running ODS v7.23UC1 on Solaris 2.5.1.. Each night, we run our optimizing routines (from a 4gl app). The routines that we use are based upon Informix's recommendation. For example, UPDATE STATISTICS MEDIUM FOR TABLE claimant DISTRIBUTIONS ONLY ; UPDATE STATISTICS HIGH FOR TABLE claimant (claimant_name,claim_no,claimant_id); Over the last week and a half (or so), we have seen a performance get real bad. In our development environment, we noticed that the execution plan was different than production/test. Hum!! Verified that indexes existed in both environments. Here's is where is gets interesting. We ran MEDIUM FOR TABLE..DIST ONLY in both test and development environments and each returned the same execution plan and also acceptable performance. Running the HIGH for each column against each environment once again changed the execution plan. We also tried fiddling around with OPTCOMPIND. No change in performance. Have you experienced strange behavior with the HIGH option? For your update statistics, do you follow informix's recommendation? If you havehad to alter there recommendation, what did you do? Thanks in advance... -- ----------------------------------------------------------------- Steve Romankiw + Executive Risk Inc. + DBA + email: sromankiw@execrisk.com 82 Hopmeadow Street + work: (860) 408-2474 Simsbury,CT 06070 + fax: (860) 408-2139 -----------------------------------------------------------------