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https://issues.apache.org/jira/browse/HIVE-949?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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He Yongqiang updated HIVE-949:
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Attachment: hive-949-2009-11-26.patch
This saves about 45% CPU time of GroupByOperator.processHashAggr. (393,686 ms
-> 216,860 ms).
> Object deepCopy in GroupBy Operator
> -----------------------------------
>
> Key: HIVE-949
> URL: https://issues.apache.org/jira/browse/HIVE-949
> Project: Hadoop Hive
> Issue Type: Improvement
> Reporter: Ning Zhang
> Assignee: He Yongqiang
> Attachments: hive-949-2009-11-26.patch
>
>
> In GroupByOperator, objects are first deep copied and then check whether or
> not the object is in the hash table (in hash-mode aggregation). In fact,
> object deep copy could be very expensive (around 5% CPU time). A simple
> change could be generate the object without deep copy through ObjectInspector
> and check its existence in the hash table. If not exists, we call deep copy.
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