关于并行的等待事件汇总：
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.
Master Note for Parallel Execution Wait Events
General Parallel Execution
| Wait Event Name | Wait Class 11.2.0.1 | Wait Class 11.1.0.7 | Wait Class 10.2.0.4 | Reference Note |
|---|---|---|---|---|
| PX slave connection | Other | Other | Other | |
| PX slave release | Other | Other | Other | |
| PX Send Wait | Other | Other | Other | |
| PX qref latch | Other | Other | Other | Note:240145.1 |
| PX create server | Other | Other | Other | |
| PX server shutdown | Other | Other | Other | Note:250357.1 |
| PX signal server | Other | Other | Other | |
| PX Deq Credit: free buffer | Other | Other | Other | |
| PX Deq: Test for msg | Other | Other | Other | |
| PX Deq: Test for credi | Other | Other | Other | |
| PX Deq: Signal ACK EXT | Other | Other | ------- | |
| PX Deq: Signal ACK RSG | Other | Other | ------- | |
| PX Deq: Signal ACK | ------- | ------- | Other | Note:257594.1 |
| PX Deq: reap credit | Other | Other | Other | |
| PX Nsq: PQ descriptor query | Other | Other | Other | |
| PX Nsq: PQ load info query | Other | Other | Other | |
| PX Deq Credit: Session Stats | Other | Other | ------- | |
| PX Deq: Slave Session Stats | Other | Other | ------- | |
| PX Deq: Slave Join Frag | Other | Other | ------- | |
| PX Deq Credit: send blkd | Idle | Idle | Other | Note:271767.1 |
| ;PX Idle Wait | Idle | Idle | Idle | Note:257595.1 |
| PX Deque wait | Idle | Idle | Idle | |
| PX Deq: Join ACK | Idle | Idle | Idle | Note:250960.1 |
| PX Deq Credit: need buffer | Idle | Idle | Idle | Note:253912.1 |
.
Parallel Query
| Wait Event Name | Wait Class 11.2.0.1 | Wait Class 11.1.0.7 | Wait Class 10.2.0.4 | Reference Note |
|---|---|---|---|---|
| PX Deq: Table Q qref | Other | Other | Other | |
| PX Deq: Table Q Get Keys | Other | Other | Other | |
| PX Deq: Table Q Close | Other | Other | Other | |
| PX Deq: Table Q Sample | Idle | Idle | Idle | |
| PX Deq: Table Q Normal | Idle | Idle | Idle | Note:270921.1 |
| PX Deq: Execution Msg | Idle | Idle | Idle | |
| PX Deq: Execute Reply | Idle | Idle | Idle | Note:270916.1 |
| PX Deq: Parse Reply | Idle | Idle | Idle | |
| PX Deq: Msg Fragment | Idle | Idle | Idle | |
| Wait Event Name | Wait Class 11.2.0.1 | Wait Class 11.1.0.7 | Wait Class 10.2.0.4 | Reference Note |
|---|---|---|---|---|
| PX Deq: Txn Recovery Start | Idle | Idle | Idle | |
| PX Deq: Txn Recovery Reply | Idle | Idle | Idle | |
| PX Deq: Par Recov Reply | ------- | ------- | Idle | |
| PX Deq: Par Recov Execute | ------- | ------- | Idle | |
| PX Deq: Par Recov Change Vector | ------- | ------- | Idle |
| Wait Event Name | Wait Class 11.2.0.1 | Wait Class 11.1.0.7 | Wait Class 10.2.0.4 | Reference Note |
|---|---|---|---|---|
| PX Deq: Merge Reply | Idle | Idle | Idle | |
| PX Deq: Index Merge Execute | Idle | Idle | Idle | |
| PX Deq: Index Merge Close | Idle | Idle | Idle | |
| Wait Event Name | Wait Class 10.2.0.4 | Wait Class 10.2.0.4 | Wait Class 10.2.0.4 | Reference Note |
|---|---|---|---|---|
| PX Deq: OLAP Update Close | Other | Other | Other | |
| PX Deq: OLAP Update Execute | Other | Other | Other | |
| PX Deq: OLAP Update Reply | Other | Other | Other | |
Parallel Query Statement Queuing
| Wait Event Name | Wait Class 11.2.0.1 | Wait Class 11.1.0.7 | Wait Class 10.2.0.4 | Reference Note |
|---|---|---|---|---|
| PX Queuing: statement queue | Scheduler | ------- | ------- | |
| enq: JX - SQL statement queue | Scheduler | ------- | ------- | |
| Wait Event Name | Wait Class 11.2.0.1 | Wait Class 11.1.0.7 | Wait Class 10.2.0.4 | Reference Note |
|---|---|---|---|---|
| PX Deq: kdcph_mai | Idle | Idle | Idle | |
| PX Deq: kdcphc_ack | Idle | Idle | Idle | |
| PX Deq: Metadata Update | Idle | ------- | ------- | |
| PX hash elem being inserted | Other | ------- | ------- | |
