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Master Note for Parallel Execution Wait Events (Doc ID 1097154.1)

Last updated on OCTOBER 01, 2019

Applies to:

Oracle Database - Enterprise Edition - Version 11.2.0.1 and later
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Information in this document applies to any platform.

Purpose

This note documents the Parallel Execution wait events.
Some of these are considered idle wait events, so you can do nothing about.
If you see  '-------' in the wait class for a version, then the wait event is not implemented in this version. 

Scope

This is intended as a reference for anyone involved in database tuning.
This Note lists the wait events and points to Reference Note where a Note is available.
At the moment we consider the following PX wait events 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 11.2.0.1
are documented here for completeness.

Details

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In this Document
Purpose
Scope
Details
 General Parallel Execution
 Parallel Query
 Parallel Recovery
 Index Operations
 OLAP Operations
 Parallel Query Statement Queuing
 Miscellaneous
 Additional Resource
References

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