Sql timings, statistics

Question

hi,
i want to test the difference between ANSI sql and oracle native sql using joins (inner, outer, left, right, full). how do i get the statistics? the timings? and where does this get displayed? into which table?
plz help on this...
thanx in advance..
Ajit

Answer 1

There are various methods and tools that you can use. You can simply set timing on and run your queries to see roughly how long it takes to execute a query once. For more exact results, you can use dbms_utility.get_time and take the difference. Better yet, you can repeat the query multiple times in a loop, and take the difference between start time and end time using dbms_utility.get_time. Below is a link to a method by Tom Kyte that does this and also provides additional information, so that you can see exactly what resources the query is using. I have included an example, below the link, of how you would use Tom Kyte's runstats_pkg to do the sort of comparison that you want to do. You will probably want to use much larger tables and loop through more times than in my brief example just to demonstrate how to do it and show the type of information that it provides. Although the times were the same in my test, you can see that there are tiny differences that may show up with larger test samples and more loops. When you have completed your testing, please post the results.
http://asktom.oracle.com/~tkyte/runstats.html
-- usage example:
scott@ORA92> SET SERVEROUTPUT ON SIZE 1000000
scott@ORA92> EXECUTE runstats_pkg.rs_start
PL/SQL procedure successfully completed.
scott@ORA92> DECLARE
  2    v_dummy NUMBER;
  3  BEGIN
  4    FOR i IN 1 .. 1000
  5    LOOP
  6        SELECT COUNT(*) INTO v_dummy
  7        FROM     emp, dept
  8        WHERE     emp.deptno = dept.deptno;
  9    END LOOP;
10  END;
11  /
PL/SQL procedure successfully completed.
scott@ORA92> EXECUTE runstats_pkg.rs_middle
PL/SQL procedure successfully completed.
scott@ORA92> DECLARE
  2    v_dummy NUMBER;
  3  BEGIN
  4    FOR i IN 1 .. 1000
  5    LOOP
  6        SELECT COUNT(*) INTO v_dummy
  7        FROM     emp INNER JOIN dept
  8        ON     emp.deptno = dept.deptno;
  9    END LOOP;
10  END;
11  /
PL/SQL procedure successfully completed.
scott@ORA92> EXECUTE runstats_pkg.rs_stop
Run1 ran in 31 hsecs
Run2 ran in 31 hsecs
run 1 ran in 100% of the time
Name                                Run1      Run2      Diff
LATCH.active checkpoint queue          0         1         1
LATCH.lgwr LWN SCN                     0         1         1
LATCH.mostly latch-free SCN            0         1         1
LATCH.redo allocation                487       489         2
STAT...calls to kcmgcs                 3         5         2
STAT...consistent gets             5,003     5,005         2
STAT...consistent gets - exami     1,003     1,005         2
STAT...cleanout - number of kt         3         5         2
STAT...active txn count during         3         5         2
LATCH.shared pool                  1,069     1,071         2
LATCH.redo writing                     0         3         3
STAT...CPU used by this sessio        23        20        -3
STAT...recursive cpu usage            20        17        -3
STAT...CPU used when call star        23        20        -3
LATCH.cache buffers chains        11,496    11,500         4
STAT...db block gets                 501       505         4
STAT...db block changes              982       986         4
STAT...consistent changes            491       495         4
LATCH.messages                         0         5         5
LATCH.library cache                2,100     2,106         6
STAT...session logical reads       5,504     5,510         6
LATCH.library cache pin            2,056     2,062         6
STAT...bytes received via SQL*     1,021     1,029         8
LATCH.checkpoint queue latch           0        32        32
STAT...redo size                  60,628    60,668        40
Run1 latches total versus runs -- difference and pct
Run1      Run2      Diff       Pct
17,257      17,320          63      99.64%
PL/SQL procedure successfully completed.