Oracle教程 2023-04-07

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

V$SESSION_WAIT_CLASS是Oracle视图。它的作用是记录每个会话的当前等待事件的等待类别。

它使用它记录等待类别和等待时间，并且可以用来查找系统中可能存在哪些等待事件。可以通过查看V$SESSION_WAIT_CLASS来评估系统性能。

要使用V$SESSION_WAIT_CLASS，你可以使用如下SQL查询它们：

SELECT sid, event#, wait_class, time_waited
FROM V$SESSION_WAIT_CLASS
WHERE sid IN (SELECT sid
FROM V$SESSION
WHERE username = ‘&user_name’);

上面的SQL语句将返回特定用户的会话空闲等待类别和等待时间。

V$SESSION_WAIT_CLASS displays the time spent in various wait event operations on a per-session basis.

Column	Datatype	Description
`SID`	`NUMBER`	Session identifier
`SERIAL#`	`NUMBER`	Serial number
`WAIT_CLASS_ID`	`NUMBER`	Identifier of the wait class
`WAIT_CLASS#`	`NUMBER`	Number of the wait class
`WAIT_CLASS`	`VARCHAR2(64)`	Name of the wait class
`TOTAL_WAITS`	`NUMBER`	Total number waits from this wait class by the session
`TIME_WAITED`	`NUMBER`	Total amount of time spent in waits from this wait class by the session (in hundredths of a second)
`TIME_WAITED_MICRO`	`NUMBER`	Total amount of time spent in waits from this wait class by the session (in microseconds)
`CPU`	`NUMBER`	Total amount of CPU time consumed by the session while implementing waits from this wait class (in microseconds)
`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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