oracle idle event list

oracle对等待事件进行了清晰的分类。其中有一类事件为idle wait。

SQL> select wait_class#,wait_class from v$system_wait_class;

WAIT_CLASS# WAIT_CLASS
----------- ----------------------------------------------------------------
0 Other
1 Application
2 Configuration
4 Concurrency
5 Commit
--  6 Idle
7 Network
8 User I/O
9 System I/O

已选择9行。

在11g下idle event共有：

SQL> select event#,name from v$event_name where wait_class#=6;

EVENT# NAME
---------- ----------------------------------------------------------------
1 pmon timer
3 VKTM Logical Idle Wait
4 VKTM Init Wait for GSGA
5 IORM Scheduler Slave Idle Wait
7 rdbms ipc message
59 i/o slave wait
65 VKRM Idle
66 wait for unread message on broadcast channel
67 wait for unread message on multiple broadcast channels
68 class slave wait
69 KSV master wait

EVENT# NAME
---------- ----------------------------------------------------------------
70 PING
72 watchdog main loop
73 DIAG idle wait
74 ges remote message
75 gcs remote message
76 heartbeat monitor sleep
77 GCR sleep
78 SGA: MMAN sleep for component shrink
109 MRP redo arrival
129 LNS ASYNC archive log
130 LNS ASYNC dest activation

EVENT# NAME
---------- ----------------------------------------------------------------
131 LNS ASYNC end of log
144 simulated log write delay
145 LGWR real time apply sync
201 parallel recovery slave idle wait
202 LogMiner builder: idle
205 LogMiner builder: branch
206 LogMiner preparer: idle
209 LogMiner reader: log (idle)
210 LogMiner reader: redo (idle)
211 LogMiner client: transaction
212 LogMiner: other

EVENT# NAME
---------- ----------------------------------------------------------------
213 LogMiner: activate
214 LogMiner: reset
215 LogMiner: find session
216 LogMiner: internal
217 Logical Standby Apply Delay
219 parallel recovery coordinator waits for slave cleanup
224 parallel recovery control message reply
231 parallel recovery slave next change
244 PX Deq: Txn Recovery Start
245 PX Deq: Txn Recovery Reply
250 fbar timer

EVENT# NAME
---------- ----------------------------------------------------------------
256 smon timer
257 PX Deq: Metadata Update
258 Space Manager: slave idle wait
260 PX Deq: Index Merge Reply
261 PX Deq: Index Merge Execute
262 PX Deq: Index Merge Close
264 PX Deq: kdcph_mai
265 PX Deq: kdcphc_ack
302 shared server idle wait
303 dispatcher timer
306 cmon timer

EVENT# NAME
---------- ----------------------------------------------------------------
307 pool server timer
309 JOX Jit Process Sleep
310 jobq slave wait
312 pipe get
315 PX Deque wait
316 PX Idle Wait
317 PX Deq: Join ACK
318 PX Deq Credit: need buffer
319 PX Deq Credit: send blkd
320 PX Deq: Msg Fragment
321 PX Deq: Parse Reply

EVENT# NAME
---------- ----------------------------------------------------------------
322 PX Deq: Execute Reply
323 PX Deq: Execution Msg
324 PX Deq: Table Q Normal
325 PX Deq: Table Q Sample
336 Streams fetch slave: waiting for txns
342 Streams: waiting for messages
343 Streams capture: waiting for archive log
347 single-task message
352 SQL*Net message from client
356 SQL*Net vector message from client
357 SQL*Net vector message from dblink

EVENT# NAME
---------- ----------------------------------------------------------------
366 PL/SQL lock timer
369 Streams AQ: emn coordinator idle wait
370 EMON slave idle wait
371 Streams AQ: waiting for messages in the queue
372 Streams AQ: waiting for time management or cleanup tasks
375 Streams AQ: delete acknowledged messages
376 Streams AQ: deallocate messages from Streams Pool
377 Streams AQ: qmn coordinator idle wait
378 Streams AQ: qmn slave idle wait
379 Streams AQ: RAC qmn coordinator idle wait
380 HS message to agent

EVENT# NAME
---------- ----------------------------------------------------------------
386 ASM background timer
392 auto-sqltune: wait graph update
393 WCR: replay client notify
394 WCR: replay clock
396 WCR: replay paused
398 JS external job
407 cell worker idle

已选择95行。

通常意义下，idle event是可以忽略的。但是有时也可以帮助我们解决问题。例如：
Whether or not the event SQL*Net message from client (and SQL*Net message from dblink) should be ignored depends on how the application works. Foreground processes post this event when they
wait for instructions from client processes. In other words, the foreground processes are sitting idle waiting for more work to do. For example, a user may run a short query and spend time looking at the result or go out to lunch without logging off. All the
while, the foreground process faithfully waits for the user to return, posting the SQL*Net message from client event and increasing the value in the TIME_WAITED column. Therefore, the SQL*Net message from client is the most prevalent event in OLTP systems,
and this is why many DBAs choose to ignore this event.

列举几个常用的 none idle 事件，对比上面的idle events。（思考一下 sql net message from client 和more from client的区别），