Oracle数据库中平均事务响应时间的计算公式

时间：2022-03-14 04:31

注：该计算公式取自：白鳝 <<oracle 优化日记>>，p316页

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