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martedì, agosto 16, 2011

AWR: %Total Call Time

Nella sezione "Top 5 Timed Events" la colonna "%Total Call Time" è calcolato come rapporto tra il tempo dell'evento d'attesa ed il "DB Time".

Nell'esempio che segue, il DB Time speso in "database user-call" è 463909, mentre il tempo di attesa sull'evento "PX Deq Credit: send blkd" è 222393.

 %Total Call Time of PX Deq Credit: send blkd => 222393/463909*100 = 47.9


Top 5 Timed Events                                         Avg %Total
~~~~~~~~~~~~~~~~~~                                        wait   Call
Event                                 Waits    Time (s)   (ms)   Time Wait Class
------------------------------ ------------ ----------- ------ ------ ----------
PX Deq Credit: send blkd          1,555,214     222,393    143   47.9      Other
db file scattered read            1,878,085      30,323     16    6.5   User I/O
db file sequential read           3,073,012      17,900      6    3.9   User I/O
CPU time                                         17,118           3.7
db file parallel read               203,998       6,165     30    1.3   User I/O
          -------------------------------------------------------------




-> Total time in database user-calls (DB Time): 463909.1s
-> Statistics including the word "background" measure background process
   time, and so do not contribute to the DB time statistic
-> Ordered by % or DB time desc, Statistic name

Statistic Name                                       Time (s) % of DB Time
------------------------------------------ ------------------ ------------
sql execute elapsed time                            462,631.7         99.7
DB CPU                                               17,117.8          3.7
parse time elapsed                                      410.4           .1
sequence load elapsed time                              392.7           .1
hard parse elapsed time                                 220.0           .0
PL/SQL execution elapsed time                             8.3           .0
connection management call elapsed time                   5.0           .0
PL/SQL compilation elapsed time                           2.1           .0
failed parse elapsed time                                 1.0           .0
hard parse (sharing criteria) elapsed time                0.6           .0
hard parse (bind mismatch) elapsed time                   0.2           .0
repeated bind elapsed time                                0.1           .0
DB time                                             463,909.1          N/A
background elapsed time                               2,561.9          N/A
background cpu time                                     806.3          N/A
          -------------------------------------------------------------

Ho notato che esiste una piccola discrepanza tra il "DB Time" riportato al top del report AWR e quello riportato più sotto nello stesso output. Infatti

              Snap Id      Snap Time      Sessions Curs/Sess
            --------- ------------------- -------- ---------
Begin Snap:      9671 10-Aug-11 00:00:24       151       2.3
  End Snap:      9676 10-Aug-11 05:00:27       156       2.2
   Elapsed:              300.04 (mins)
   DB Time:            7,731.82 (mins)

mentre

-> Total time in database user-calls (DB Time): 463909.1s


7731 minuti sono 463860 secondi (7731*60 ). La discrepanza è di 49 secondi.

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