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https://issues.apache.org/jira/browse/HIVE-1900?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12978987#action_12978987
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Namit Jain commented on HIVE-1900:
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1. Why should it be any different than sort-merge join ?
ExecMapper needs to keep track of the current file, and then change the
partitioning columns whenever the file changes
2. Why should it matter ?
3. Why should it matter ?
> a mapper should be able to span multiple partitions
> ---------------------------------------------------
>
> Key: HIVE-1900
> URL: https://issues.apache.org/jira/browse/HIVE-1900
> Project: Hive
> Issue Type: Improvement
> Components: Query Processor
> Reporter: Namit Jain
> Assignee: He Yongqiang
>
> Currently, a mapper only spans a single partition which creates a problem in
> the presence of many
> small partitions (which is becoming a common usecase in facebook).
> If the plan is the same, a mapper should be able to span files across
> multiple partitions
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