오라클 이벤트 클래스( WAIT_EVENT_CLASS )
Every oracle wait event belongs to a class of wait event. Here is the list of classes of oracle wait events.
1)Administrative: DBA commands cause users to wait. Example: index rebuild
2)Application: User application codes cause to wait. Example: row level lock
3)Cluster: Waits related to Real Application Cluster resources. Example: gc cr block busy
4)Commit: After issuing commit wait for redo log write confirmation. Example: log file sync
5)Concurrency: Waits for internal database resources. Example: Latch wait.
6)Configuration: Waits caused by inadequate configuration of database or instance resources Example: Undersized log file size, undersized shared pool size.
7)Idle: Waits that signify the session is inactive, that is session waiting for work. Example: SQL*Net message from client.
8)Network: Waits related to network messaging. Example: SQL*Net more data to dblink.
9)Other: Waits which should not typically occur on a system. Example:wait for EMON to spawn.
10)Scheduler: Resource Manager related waits. Example: resmgr: become active.
11)System I/O: Waits for background process IO. Example: DBWR waits for 'db file parallel write'.
12)User I/O: Waits for user IO. Example: 'db file sequential read'