I noticed that when I execute a query more than one time consecutively on my mysql machine, the execution time drops and changes significantly (40/50%) after the first execution, and that WITHOUT query cache activated and no other processes interfering.
I suspect that there is some "hidden" caching involved, like temporary tables, specially when the query involves several subqueries, or maybe some disk IO cache, but I don't understand it really.
Since sometimes I need to fine tune some queries, I don't know how to deal with this problem. What I do usually, is to run the query several times and get rid of the peaks
I'd like to know if there is a better solution...