每一个等待事件都属于某一类，下面给出了每一类等待事件的描述。【Every wait event belongs to a class of wait event. The following list describes each of the wait classes.】
管理类：Administrative
此类等待事件是由于DBA的管理命令引起的，这些命令要求用户处于等待状态，比如，重建索引。【Waits resulting from DBA commands that cause users to wait (for example, an index rebuild)】
应用程序类：Application
此类等待事件是由于用户应用程序的代码引起的（比如：锁等待）【Waits resulting from user application code (for example, lock waits caused by row level locking or explicit lock commands)】
群集类：Cluster
此类等待事件和真正应用群集RAC的资源有关。（比如：gc cr block busy等待事件）【Waits related to Real Application Cluster resources (for example, global cache resources such as 'gc cr block busy'】
提交确认类：Commit
此类等待事件只包含一种等待事件－－在执行了一个commit命令后，等待一个重做日志写确认（也就是log file sync）【This wait class only comprises one wait event - wait for redo log write confirmation after a commit (that is, 'log file sync')】
并发类：Concurrency
此类等待事件是由内部数据库资源引起的，比如闩锁。【Waits for internal database resources (for example, latches)】
配置类：Configuration
此类等待事件是由数据库或实例的不当配置造成的，比如，重做日志文件尺寸太小，共享池的大小等。【Waits caused by inadequate configuration of database or instance resources (for example, undersized log file sizes, shared pool size)】
空闲类：Idle
此类等待事件意味着会话不活跃，等待工作。比如,sql * net messages from client。【Waits that signify the session is inactive, waiting for work (for example, 'SQL*Net message from client')】
网络类：Network
和网络环境相关的一些等待事件，比如sql* net more data to dblink。【Waits related to network messaging (for example, 'SQL*Net more data to dblink')】
Other
此类等待事件通常比较少见。【Waits which should not typically occur on a system (for example, 'wait for EMON to spawn')】
调度类：Scheduler
Resource Manager related waits (for example, 'resmgr: become active')
系统I/O类：System I/O
此类等待事件通过是由后台进程的I/O操作引起的，比如DBWR等待，db file paralle write。【Waits for background process IO (for example, DBWR wait for 'db file parallel write')】
用户I/O类：User I/O
此类等待事件通常是由用户I/O操作引起的,比如db file sequential read。【Waits for user IO (for example 'db file sequential read')】
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