Hi, I've searched the web but can't find an answer to my problem. I've taken a copy of my production database and restored it onto my test environment and a specific select query takes about 8 seconds on the production server and about 8 minutes in test. I've reviewed the query plan and they both use the same indexes however on production it's doing a clustered index seek and on test it's doing a clustered index scan. I've updated the statistics, reindexed the table and even completely dropped the index and recreated it with little change. My question is, what else effects the optimisers choice? Could it be because my test kit is lower spec, if so whats going to be the most likely cause, memory, disk sub system, something else?