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it's not safe to automatically turn on intraparallel feature... db2 optimizer is based on cost estimation, and note this "estimation" is just a heuristic, which could be not accurate or perfectly represent the real runtime cost, especially when there's data skew exist. So in the case when DB2 detects intraparallel could be benefit for the query, we still need to be careful whether really turn on the feature because it may severely affect general performance if the estimation is incorrect, or the box is already bounded by CPU resources. As an experienced DBA you should have idea what your system workload looks like, and should make the decision whether turn on intraparallel feature or not. |
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楼主: ~贝贝~
IP卡
狗仔卡
发表于 2011-6-1 19:26
显身卡
楼主
发表于 2011-6-2 17:16
