My Oracle Support Banner

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

Last updated on SEPTEMBER 20, 2022

Applies to:

Oracle Database - Enterprise Edition - Version and later
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Gen 1 Exadata Cloud at Customer (Oracle Exadata Database 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.


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. 


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
are documented here for completeness.


To view full details, sign in with your My Oracle Support account.

Don't have a My Oracle Support account? Click to get started!

In this Document
 General Parallel Execution
 Parallel Query
 Parallel Recovery
 Index Operations
 OLAP Operations
 Parallel Query Statement Queuing
 Additional Resource

My Oracle Support provides customers with access to over a million knowledge articles and a vibrant support community of peers and Oracle experts.