Oracle教程 2023-04-06

Oracle 视图 V$EVENTMETRIC 官方解释，作用，如何使用详细说明

_HISIORY

Oracle数据库提供了视图V$EVENTMETRIC_HISTORY来查看系统中各个数据库事件的性能数据。它显示了一段时间内（如一小时，一天，一周等）各个事件（如等待事件，消耗时间等）的性能数据。

要使用V$EVENTMETRIC_HISTORY视图，首先登录到Oracle数据库，然后创建一个数据库会话并在其中实行该视图：

SQL> select * from V$EVENTMETRIC_HISTORY;

该语句将显示各个数据库事件的性能数据，其帮助DBA更好地理解系统性能，并将其加以优化。

V$EVENTMETRIC displays values of wait event metrics for the most recent 60-second interval.

Column	Datatype	Description
`BEGIN_TIME`	`DATE`	Begin time of the interval
`END_TIME`	`DATE`	End time of the interval
`INTSIZE_CSEC`	`NUMBER`	Interval size (in hundredths of a second)
`EVENT#`	`NUMBER`	Number of the event
`EVENT_ID`	`NUMBER`	Identifier of the event
`NUM_SESS_WAITING`	`NUMBER`	Number of sessions waiting at the end of the interval
`TIME_WAITED`	`NUMBER`	Time waited (in hundredths of a second)
`WAIT_COUNT`	`NUMBER`	Number of times waited
`TIME_WAITED_FG`	`NUMBER`	Time waited (in hundredths of a second), from foreground sessions
`WAIT_COUNT_FG`	`NUMBER`	Number of times waited, from foreground sessions
`CON_ID`	`NUMBER`	The ID of the container to which the data pertains. Possible values include: `0`: This value is used for rows containing data that pertain to the entire CDB. This value is also used for rows in non-CDBs. `1`: This value is used for rows containing data that pertain to only the root n: Where n is the applicable container ID for the rows containing data

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