Hi all, I need to know the actual execution time of a query, but considering that the data is already cached. I also need to make sure that cached data from other queries is cleared. I believe that in order to know the real time of a query it will be necessary to "warm up" the data to be inserted in cache.
Below are the steps suggested by a DBA for me: Step 1- run ANALYZE on all tables involved before the test; Step 2- restart the DBMS (to clear the DBMS cache); Step 3- erase the S.O. cache; Step 4- execute at least 5 times the same query. After the actual execution time of the query, it would have to take the time of the query that is in the "median" among all. Example: Execution 1: 07m 58s Execution 2: 14m 51s Execution 3: 17m 59s Execution 4: 17m 55s Execution 5: 17m 07s In this case to calculate the median, you must first order each execution by its time: Execution 1: 07m 58s Execution 2: 14m 51s Execution 5: 17m 07s Execution 4: 17m 55s Execution 3: 17m 59s In this example the median would be execution 5 (17m 07s). Could someone tell me if this is a good strategy ? Due to being a scientific work, if anyone has a reference of any article or book on this subject, it would be very useful. Best Regards Neto