Optimizer Info

I am running 7.1 on Solaris 2.5 (soon to be upgrading to 7.24). Are there any ways to know how the optimizer is evaluating all the possible query plans and how it decides which one it chooses. I know about 'set explain' and data distributions and such, but is there a way to see the process the optimizer went through. I guess I am looking for a trace of the optimizer and not just the end result. We are in the process of doing some serious analysis of our query plans and we are trying to see what influences the optimizer etc. Also can you 'tell' or hint the optimizer what order to do joins or what indexes you would like to use, or is it just up to the optimizer. I realize the way SQL is contructed will affect the plan chosen, however I think other DBMSs offer the ability to indicate the indexes to use via the SQL. Books and/or other resources would be helpful. Thanks. ====================================== Maurice Fontaine maurice.fontaine@fmr.com ======================================