Common wait events

 

대기 이벤트명	영역	점검대상
Buffer busy wait	버퍼캐시, DBWR	문제 발생시에 v$session_wait
Free buffer waits	버퍼캐시, DBWR	OS통계통한 write speed 검토, 버퍼캐시 통계
db file scattered read, db file sequential read	I/O, SQL튜닝	v$sqlarea PHYSICAL_READ_REQUESTS, v$filestat readtim
enqueue waits (enq:)	LOCK	v$enqueue_stat
library cache waits	Latch	v$sqlarea parsing calls, child cursor
log buffer space	log buffer, lgwr	v$sysstat 'redo buffer allocation retries', 디스크성능
log file sync	over commit, lgwr	v$sysstat 'user commits'+'user rollbacks', 디스크성능