Re: Inconsistent SQL tuning results

  • From: "Daniel W. Fink" <daniel.fink@xxxxxxxxxxxxxx>
  • To: michaeljmoore@xxxxxxxxx
  • Date: Mon, 07 Feb 2011 10:59:44 -0700

Without additional information, the only option available is "Guess".
Run extended sql trace (dbms_monitor.session_trace_enable, event 10046, etc), run the trace file(s) through tkprof and analyze the differences. 


On 2/7/2011 10:49 AM, Michael Moore wrote:
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



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