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https://issues.apache.org/jira/browse/HIVE-12369?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16447200#comment-16447200
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Matt McCline commented on HIVE-12369:
-------------------------------------
The days when I hate git.
fatal: git apply: bad git-diff - inconsistent old filename on line 7887
> Native Vector GroupBy (Part 1)
> ------------------------------
>
> Key: HIVE-12369
> URL: https://issues.apache.org/jira/browse/HIVE-12369
> Project: Hive
> Issue Type: Bug
> Components: Hive
> Reporter: Matt McCline
> Assignee: Matt McCline
> Priority: Critical
> Attachments: HIVE-12369.01.patch, HIVE-12369.02.patch,
> HIVE-12369.05.patch, HIVE-12369.06.patch, HIVE-12369.091.patch,
> HIVE-12369.094.patch, HIVE-12369.095.patch, HIVE-12369.096.patch,
> HIVE-12369.097.patch, HIVE-12369.098.patch, HIVE-12369.099.patch
>
>
> Implement Native Vector GroupBy using fast hash table technology developed
> for Native Vector MapJoin, etc.
> Patch is currently limited to a single COUNT aggregation. Or, no aggregation
> also known as duplicate reduction.
> Here are examples of new kinds of classes introduces that stored the count in
> the slot table and don't allocate hash elements:
> {noformat}
> COUNT(column) VectorGroupByHashLongKeySingleCountColumnOperator
> COUNT(key) VectorGroupByHashLongKeySingleCountKeyOperator
> COUNT(*) VectorGroupByHashLongKeySingleCountStarOperator
> {noformat}
> And the duplicate reduction operator a single key. Example:
> {noformat}
> VectorGroupByHashLongKeyDuplicateReductionOperator
> {noformat}
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