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From "He Yongqiang (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HIVE-949) Object deepCopy in GroupBy Operator
Date Fri, 27 Nov 2009 00:22:39 GMT

     [ https://issues.apache.org/jira/browse/HIVE-949?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

He Yongqiang updated HIVE-949:
------------------------------

    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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