Master Note Parallel Execution Wait Events

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Master Note Parallel Execution Wait Events (Doc ID 1097154.1)

Applies to:

Oracle Server - Enterprise Edition - Version: and later   [Release: 11.2 and later ]
Information in this document applies to any platform.


This note documents the Parallel Execution wait events.
Some of these can be considered as 'events which you can do nothing about so don't bother looking at them'.We also say to this events idle wait events.
If you see  '-------' in the wait class for a version, then the wait event is not implemented in this version. 


This is intended as a reference for anyone involved in database tuning.
This Note list the wait events and points to Reference Note where a Note is available.

At the moment we consider the following PX wait events as idle:
---PX Deq: Txn Recovery Start
---PX Deq: Txn Recovery Reply
---PX Deq: Metadata Update
---PX Deq: Index Merge Reply
---PX Deq: Index Merge Execute
---PX Deq: Index Merge Close
---PX Deq: kdcph_mai
---PX Deq: kdcphc_ack
---PX Deque wait
---PX Idle Wait
---PX Deq: Join ACK
---PX Deq Credit: need buffer
---PX Deq Credit: send blkd
---PX Deq: Msg Fragment
---PX Deq: Parse Reply
---PX Deq: Execute Reply
---PX Deq: Execution Msg
---PX Deq: Table Q Normal
---PX Deq: Table Q Sample

The full list of Parallel Execution wait events in
are documented here for completeness.

Master Note Parallel Execution Wait Events

Parallel Execution Wait Events

General Parallel Execution

Wait Event NameWait Class Class Class Note
PX slave connectionOtherOtherOther
PX slave releaseOtherOtherOther
PX Send WaitOtherOtherOther
PX qref latchOtherOtherOtherNote:240145.1
PX create serverOtherOtherOther
PX server shutdownOtherOtherOtherNote:250357.1
PX signal serverOtherOtherOther
PX Deq Credit: free bufferOtherOtherOther
PX Deq: Test for msgOtherOtherOther
PX Deq: Test for crediOtherOtherOther
PX Deq: Signal ACK EXTOtherOther-------
PX Deq: Signal ACK RSGOtherOther-------
PX Deq: Signal ACK--------------OtherNote:257594.1
PX Deq: reap creditOtherOtherOther
PX Nsq: PQ descriptor queryOtherOtherOther
PX Nsq: PQ load info queryOtherOtherOther
PX Deq Credit: Session StatsOtherOther-------
PX Deq: Slave Session StatsOtherOther-------
PX Deq: Slave Join FragOtherOther-------
PX Deq Credit: send blkdIdleIdleOtherNote:271767.1
;PX Idle WaitIdleIdleIdleNote:257595.1
PX Deque waitIdleIdleIdle
PX Deq: Join ACKIdleIdleIdleNote:250960.1
PX Deq Credit: need bufferIdleIdleIdleNote:253912.1


Parallel Query

Wait Event NameWait Class Class Class Note
PX Deq: Table Q qrefOtherOtherOther
PX Deq: Table Q Get KeysOtherOtherOther
PX Deq: Table Q CloseOtherOtherOther
PX Deq: Table Q SampleIdleIdleIdle
PX Deq: Table Q NormalIdleIdleIdleNote:270921.1
PX Deq: Execution MsgIdleIdleIdle
PX Deq: Execute ReplyIdleIdleIdle
PX Deq: Parse ReplyIdleIdleIdle
PX Deq: Msg FragmentIdleIdleIdle

Parallel Recovery
Wait Event NameWait Class Class Class Note
PX Deq: Txn Recovery StartIdleIdleIdle
PX Deq: Txn Recovery ReplyIdleIdleIdle
PX Deq: Par Recov Reply--------------Idle
PX Deq: Par Recov Execute--------------Idle
PX Deq: Par Recov Change Vector--------------Idle

Index Operations
Wait Event NameWait Class Class Class Note
PX Deq: Merge ReplyIdleIdleIdle
PX Deq: Index Merge ExecuteIdleIdleIdle
PX Deq: Index Merge CloseIdleIdleIdle

OLAP Operations

Wait Event NameWait Class Class Class Note
PX Deq: OLAP Update CloseOtherOtherOther
PX Deq: OLAP Update ExecuteOtherOtherOther
PX Deq: OLAP Update ReplyOtherOtherOther

Parallel Query Statement Queuing

Wait Event NameWait Class Class Class Note
PX Queuing: statement queueScheduler--------------
enq: JX - SQL statement queueScheduler--------------


Wait Event NameWait Class Class Class Note
PX Deq: kdcph_maiIdleIdleIdle
PX Deq: kdcphc_ackIdleIdleIdle
PX Deq: Metadata UpdateIdle--------------
PX hash elem being insertedOther--------------

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