Oracle Parallel Query Wait Events

This note documents the Parallel Execution wait events (as of 9.2).
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.

This is intended as a reference for anyone involved in database tuning.
At the moment we consider the following PX wait events as idle:
- "PX Idle Wait"
- "PX Deq: Execution Msg"
- "PX Deq: Table Q Normal"
- "PX Deq Credit: send blkd"
- "PX Deq: Execute Reply"
- "PX Deq Credit: need buffer"
- "PX Deq: Signal ACK"
- "PX Deque wait"
In 9i statspack does not filter out all idle PX wait event in
the Top 5 wait event section. So it can happen that you see
a PX idle wait event in this section.
The full list of Parallel Execution wait events are documented here
for completeness.
Parallel Execution Wait Events
------------------------------



Parallel Recovery
=================
"PX Deq: Par Recov Reply"
Note:69112.1
"PX Deq: Par Recov Execute"
Note:69111.1
"PX Deq: Par Recov Change Vector"
Note:69110.1
knp.h
Replication
===========
"Replication Dequeue "
kna.h
"waiting for slave message"
kxfq.h
Parallel Query
==============
"PX Deq: Table Q Normal" Note:270921.1
"PX Deq: Table Q Sample"
Note:60708.1;
"PX Deq: Table Q qref"
Note:60710.1
"PX Deq: Table Q Get Keys"
Note:60707.1
"PX Deq: Table Q Close"
Note:69072.1
kdi.h

Index Operations
================
"PX Deq: Merge Reply"
Note:69109.1
"PX Deq: Index Merge Execute"
Note:69108.1
"PX Deq: Index Merge Close"
Note:69107.1
kxfp.h
General Parallel Execution
==========================
"PX qref latch" Note:240145.1
"PX server shutdown" Note:250357.1
"PX create server" obsolete since Oracle 8.0
"PX signal server"
Note:34599.1 
"PX Deque wait"
Note:34596.1
"PX Idle Wait" Note:257595.1
"PX Deq: Join ACK" Note:250960.1
"PX Deq Credit: need buffer" Note:253912.1
"PX Deq Credit: free buffer"
Note:60721.1
"PX Deq Credit: send blkd"
Note:60723.1
"PX Deq: Test for msg"
Note:60720.1 
"PX Deq: Signal ACK" Note:257594.1
"PX Deq: reap credit" Note:250947.1
"PX Nsq: PQ descriptor query"
"PX Nsq: PQ load info query"
kxfx.h
"PX Deq: Msg Fragment" Note:254760.1
"PX Deq: Parse Reply" Note:257596.1
"PX Deq: Execute Reply" Note:270916.1
"PX Deq: Execution Msg" Note:69067.1
ktpr.h
Parallel Transaction Recovery
=============================
"PX Deq: Txn Recovery Start"
Note:69114.1
"PX Deq: Txn Recovery Reply"
Note:69115.1 ‎



 

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