Oracle 空閒等待事件

       查v$system_event和v$session_event裡的事件資訊時，有些是空閒事件無需關心。比如說 “SQL*Net message from client”這個事件，是server程式在等待客戶端發sql指令。只要不是網路出問題，這樣的事件不用關心。

       可以用statspack的stats$idle_event表裡記錄的專案，來確定哪些是空閒等待事件。在spctab.sql中有stats$idle_event的描述。空閒事件包括有（Oracle 10g）：

'smon timer', 'pmon timer', 'rdbms ipc message', 'Null event', 'parallel query dequeue', 'pipe get', 'client message', 'SQL*Net message to client', 'SQL*Net message from client', 'SQL*Net more data from client', 'dispatcher timer', 'virtual circuit status', 'lock manager wait for remote message', 'PX Idle Wait', 'PX Deq: Execution Msg', 'PX Deq: Table Q Normal', 'wakeup time manager', 'slave wait', 'i/o slave wait', 'jobq slave wait', 'null event', 'gcs remote message', 'gcs for action', 'ges remote message', 'queue messages', 'wait for unread message on broadcast channel', 'PX Deq Credit: send blkd', 'PX Deq: Execute Reply', 'PX Deq: Signal ACK', 'PX Deque wait', 'PX Deq Credit: need buffer', 'STREAMS apply coord waiting for slave message',  'STREAMS apply slave waiting for coord message',  'Queue Monitor Wait',  'Queue Monitor Slave Wait',  'wakeup event for builder',  'wakeup event for preparer',  'wakeup event for reader',  'wait for activate message',  'PX Deq: Par Recov Execute', 'PX Deq: Table Q Sample', 'STREAMS apply slave idle wait', 'STREAMS capture process filter callback wait for ruleset', 'STREAMS fetch slave waiting for txns', 'STREAMS waiting for subscribers to catch up', 'Queue Monitor Shutdown Wait', 'AQ Proxy Cleanup Wait', 'knlqdeq', 'class slave wait', 'master wait', 'DIAG idle wait', 'ASM background timer', 'KSV master wait', 'EMON idle wait', 'Streams AQ: RAC qmn coordinator idle wait', 'Streams AQ: qmn coordinator idle wait', 'Streams AQ: qmn slave idle wait', 'Streams AQ: waiting for time management or cleanup tasks', 'Streams AQ: waiting for messages in the queue', 'Streams fetch slave: waiting for txns', 'Streams AQ: deallocate messages from Streams Pool', 'Streams AQ: delete acknowledged messages', 'LNS ASYNC archive log', 'LNS ASYNC dest activation', 'LNS ASYNC end of log', 'LogMiner: client waiting for transaction', 'LogMiner: slave waiting for activate message', 'LogMiner: wakeup event for builder', 'LogMiner: wakeup event for preparer', 'LogMiner: wakeup event for reader'。

通常我們可以用下面的方式來過濾：

event not like 'SQL*NET%' and event not like 'smon%' and event not like 'pmon%' and event not like 'rdbms%' and event not like 'PX%' and event not like 'sbt%' and event not in ('gcs remote message', 'ges remote message', 'virtual circuit status', 'dispatcher timer');