Expert Oracle Exadata - Parent Directory

CHAPTER 11 UNDERSTANDING EXADATA PERFORMANCE METRICS403, TANEL , STAT, cell physical IO interconnect bytes returned by smart scan, 1.6M403, TANEL , STAT, cell blocks processed by cache layer , 1.35M403, TANEL , STAT, cell blocks processed by txn layer , 1.35M403, TANEL , STAT, cell blocks processed by data layer , 1.35M403, TANEL , STAT, cell blocks helped by minscn optimization , 1.35M403, TANEL , STAT, cell IO uncompressed bytes , 11.05G403, TANEL , WAIT, cell smart table scan , 4.07s-- End of Stats snap 1, end=2011-04-03 19:07:36, seconds=5---------------------------------------------------------------------------------Active% | SQL_ID | EVENT | WAIT_CLASS---------------------------------------------------------------------------------95% | b7z0fth0asbbt | cell smart table scan | User I/O5% | b7z0fth0asbbt | ON CPU | ON CPU-- End of ASH snap 1, end=2011-04-03 19:07:36, seconds=5, samples_taken=42This output shows that during the 5-second monitoring time, the session 403 did 1.34 million logicalreads, and it read 11.03GB of data using about 10530 multiblock read I/O requests (large numbers areconverted into humanfriendly approximations here, but Snapper can also print out exact figures).The next example shows how you can use Snapper on a parallel query. Notice the qc=403 option,which tells Snapper to capture stats for all PX slaves of Query Coordinator SID 403. Also notice thesinclude option, which allows you to list only the metrics of interest using a regular expression:SQL> @snapper ash,stats,gather=s,sinclude=physical.*total.*bytes|cell.*scan 5 1 qc=403Sampling SID qc=403 with interval 5 seconds, taking 1 snapshots...-- Session Snapper v3.52 by Tanel Poder @ E2SN ( http://tech.e2sn.com )------------------------------------------------------------------------------------------SID, USER , TYPE, STATISTIC , HDELTA------------------------------------------------------------------------------------------12, TANEL , STAT, physical read total bytes , 2.86G12, TANEL , STAT, cell physical IO interconnect bytes returned by smart scan , 411.16k12, TANEL , STAT, cell scans , 255, TANEL , STAT, physical read total bytes , 3.05G55, TANEL , STAT, cell physical IO interconnect bytes returned by smart scan, 443.54k55, TANEL , STAT, cell scans , 3113, TANEL , STAT, physical read total bytes , 2.97G113, TANEL , STAT, cell physical I/O interconnect bytes returned by smart scan , 432.29k113, TANEL , STAT, cell scans , 3159, TANEL , STAT, physical read total bytes , 2.63G159, TANEL , STAT, cell physical I/O interconnect bytes returned by smart scan , 381.37k159, TANEL , STAT, cell scans , 2-- End of Stats snap 1, end=2011-04-03 19:57:35, seconds=6353