RAC单实例执行并行查询，为什么并行度一直是1？ - Oracle数据库管理 Oracle数据库数据恢复、性能优化

Oracle数据库数据恢复、性能优化»论坛 › Oracle › Oracle数据库管理 › RAC单实例执行并行查询，为什么并行度一直是1？ ...

1^#

发表于 2013-3-15 09:32:43

alter sytsem flush shared_pool;

alter session set events '10053 trace name context forever,level 1';
alter session set "_px_trace"="compilation","execution","messaging";

运行你的语句

把生成的TRACE上传

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Maclean Liu(刘相兵

2^#

发表于 2013-3-15 10:49:03

**************************
Automatic degree of parallelism (ADOP)
**************************
Automatic degree of parallelism is enabled for this statement in hint mode.
kkopqSetDopReason: Reason why we chose this DOP is: hint.
Hint forces parallelism with dop=3

kxfplist
      Getting instance info for default group
kxfpGetTotalCpuCount
      kxfplist returned status: 2
kxfrDefaultDOP
      DOP Trace -- compute default DOP
         # CPU    = 1
         Threads/CPU = 2 ("parallel_threads_per_cpu")
         default DOP = 2 (# CPU * Threads/CPU)
         # instance alive = 0 (kxfpFindAvailableInstCnt)
         parallel_instance_group has no instance members so             de
         fault DOP = 1Default DOP = 1

AUTO DOP PLANS EVALUATION
***************************************
Compilation completed with Dop: 3.
  Cost_io:  292.00  Cost_cpu: 18671705.12
  Card:    1.00  Bytes: 0.00
  Cost:    292.58  Est_time:  3516ms
AutoDop: kkopqSetMaxDopInCursorEnv:In the Cursor Session Env, max DOP is set to 65535
*****************************
Number of Compilations tried: 1
*****************************

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Maclean Liu(刘相兵

3^#

发表于 2013-3-15 10:52:57

kxfpFindAvailableInstCnt ==> instance alive = 0

session退出再登陆试试

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Maclean Liu(刘相兵

4^#

发表于 2013-3-15 11:57:37

有空我在11.2.0.3 上测一下，可能是配置问题，也可能是bug

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