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https://issues.apache.org/jira/browse/HIVE-20985?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16704012#comment-16704012
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Zoltan Haindrich commented on HIVE-20985:
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yes; it disables reuse inside a select expression; I think we can't reuse
possible inputs during expression evaluation.
If those columns may contain non-needed reusable parts - then they are not
freed when they became un-needed. But I think we need consistency and then fix
reuse.
note: I think un-needed columns are not transfered - as I think after a vector
operator is executed only outputcolumns are taken forward; temporary
computations are left out; so even thru higher indexed columns are used; the
data volume will not increase.
> If select operator inputs are temporary columns vectorization may reuse some
> of them as output
> ----------------------------------------------------------------------------------------------
>
> Key: HIVE-20985
> URL: https://issues.apache.org/jira/browse/HIVE-20985
> Project: Hive
> Issue Type: Bug
> Components: Vectorization
> Reporter: Zoltan Haindrich
> Assignee: Zoltan Haindrich
> Priority: Major
> Attachments: HIVE-20985.01.patch, HIVE-20985.02.patch
>
>
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