Oracle数据库中平均事务响应时间的计算公式

Oracle数据库中平均事务响应时间的计算公式

 

注: 该计算公式取自:白鳝 <<oracle 优化日记>>p316

 

Top 5 Timed Events

Event Waits Time(s) Avg Wait(ms) % Total Call Time Wait Class
direct path read 327,284 15,555 48 86.4 User I/O
CPU time   1,093   6.1  
db file sequential read 283,101 509 2 2.8 User I/O
db file scattered read 99,520 180 2 1.0 User I/O
enq: TX - row lock contention 274 133 485 .7 Application

 

Wait Events

  • s - second
  • cs - centisecond - 100th of a second
  • ms - millisecond - 1000th of a second
  • us - microsecond - 1000000th of a second
  • ordered by wait time desc, waits desc (idle events last)

Event Waits %Time -outs Total Wait Time (s) Avg wait (ms) Waits /txn
direct path read 327,284 0.00 15,555 48 32.66
db file sequential read 283,101 0.00 509 2 28.25
db file scattered read 99,520 0.00 180 2 9.93
enq: TX - row lock contention 274 98.91 133 485 0.03
log file sync 6,791 0.00 93 14 0.68
control file sequential read 16,168 0.00 91 6 1.61
log file parallel write 7,816 0.00 82 10 0.78
name-service call wait 1,199 0.42 68 57 0.12

 

以"direct path read"这个等待事件为例子来计算:

A---"direct path read" 的  Total Wait Time(以ms来计算)为15555*1000=15555000ms

B---"direct path read" 的   Waits 为327284

C---"direct path read" 的   Waits /txn   为32.66

D---"direct path read" 的   % Total Call Time 为 86.4%=0.864


平均事务响应时间=A/B*C/D=15555000/327284*32.66/0.864=1796.584626 ms


 

 

 

 

 

 

 

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