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From "He Yongqiang (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HIVE-1802) Encode MapReduce Shuffling Keys Differently for Single string/bigint Key
Date Tue, 23 Nov 2010 18:25:13 GMT

    [ https://issues.apache.org/jira/browse/HIVE-1802?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12934957#action_12934957
] 

He Yongqiang commented on HIVE-1802:
------------------------------------

For one Text key in join, i think in your patch you still need an array copy.  For one Text
key in group by, array copy is not needed.

I mean the new code only process one Text key in Group by, which we can avoid array copy.

For other cases, maybe we can optimize BinarySortableSerDe to use array copy instead of write?

> Encode MapReduce Shuffling Keys Differently for  Single string/bigint Key
> -------------------------------------------------------------------------
>
>                 Key: HIVE-1802
>                 URL: https://issues.apache.org/jira/browse/HIVE-1802
>             Project: Hive
>          Issue Type: Improvement
>            Reporter: Siying Dong
>            Assignee: Siying Dong
>         Attachments: HIVE-1802.1.patch
>
>
> Delimiters are not needed if we only have one shuffling key, and in the same time escaping
delimiters are not needed. We can save some CPU time on serializing and shuffle slightly less
amount of data to save memory footprint and network traffic.
> Also there is a bug that for group-by, we by mistake add a -1 to the end of the key and
pay one more unnecessary mem-copy. Can be easily fixed.

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