V$SESSION

WAIT_TIME

NUMBER

If the session is currently waiting, then the value is 
0
. If the session is not in a wait, then the value is as follows:

> 
0
 - Value is the duration of the last wait in hundredths of a second

-1
 - Duration of the last wait was less than a hundredth of a second

-2
 - Parameter 
TIMED_STATISTICS
 was set to 
false

This column has been deprecated in favor of the columns 
WAIT_TIME_MICRO
 and 
STATE
.

1.当会话的state为waiting时，wait_time为0.

2.wait_time 大于0时，指的是从上一次waiting到当前非waiting状态的间隔时间，单位为1/100秒。

3.wait_time为-1时，指的是从上一次waiting到当前非waiting状态的间隔时间小于1/100秒。

4.wait_time为-2时，TIMED_STATISTICS 设成了fasle。

V$ACTIVE_SESSION_HISTORY

WAIT_TIME

NUMBER

0
 if the session was waiting at the time of sampling

Total wait time for the event for which the session last waited if the session was on the CPU when sampled

Whether or not 
WAIT_TIME
 = 
0
 is what is useful to find the 
SESSION_STATE
 at the time of sampling, rather than the actual value of 
WAIT_TIME
 itself. 
Maps to V$SESSION.WAIT_TIME
.

1.wait_time为0 ，当在采样时，会话状态是waiting。

2.wait_time大于0,当在采样时，会话状态是on cpu，这个值便是从往上最后一次状态为waitting到当前的时间区间。

3.这里的采样频率是1s.

DBA_HIST_ACTIVE_SESS_HISTORY

WAIT_TIME

NUMBER

Total wait time (in microseconds) for the event for which the session last waited (
0
 if currently waiting)

1.wait_time为0 ，当在采样时，会话状态是waiting。

2.wait_time大于0,当在采样时，会话状态是on cpu，这个值便是从往上最后一次状态为waitting到当前的时间区间。

3.这里的采样频率是10s.

ITPub博客

session视图中wait_time

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