I've been trying to tune a SQL statement but I get very inconsistent results. I always start with: alter system flush shared_pool; alter system flush buffer_cache; Then I run the SQL, but the first time I run it, it can take as much as 7 minutes. On the 2nd, 3rd, and 4th runs, it takes 40 sec, 49 sec, 35 sec respectively. So my question is: What might account for the huge difference in run time between the first run and successive runs? Thanks, Mike