oracle AWR报告DB time和DB cpu

DB time = DB cpu + Non-idle wait + Wait on cpu queue

即DB time 大致相当于 DB cpu + 非空闲等待。因为如果cpu利用率没有到达100%，一般不会有 wait on cpu queue。

Statistic Name	Description
DB Time	Amount of elapsed time (in microseconds) spent performing Database user-level calls. This does not include the elapsed time spent on instance background processes such as PMON.
DB CPU	Amount of CPU time (in microseconds) spent on database user-level calls. This does not include the CPU time spent on instance background processes such as PMON.

以下摘自官方文档：

Home / Database / Oracle Database Online Documentation 11g Release 2 (11.2) / Database Administration

5.1.1.2 Time Model Statistics

The most important of the time model statistics is DB time. This statistics represents the total time spent in database calls and is an indicator of the total instance workload. It is calculated by aggregating the CPU and wait times of all sessions not waiting on idle wait events (non-idle user sessions).

DB time is measured cumulatively from the time of instance startup. Because DB time it is calculated by combining the times from all non-idle user sessions, it is possible that the DB time can exceed the actual time elapsed after the instance started. For example, an instance that has been running for 30 minutes could have four active user sessions whose cumulative DB time is approximately 120 minutes.