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https://issues.apache.org/jira/browse/HIVE-16602?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16190524#comment-16190524
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Jesus Camacho Rodriguez commented on HIVE-16602:
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[~kellyzly], it will depend on the scale and your hw indeed. For instance, in
our case we could confirm that it made a huge difference for a few TCP-DS
queries when we were benchmarking Hive at 10TB scale (more info in
https://hortonworks.com/blog/3x-faster-interactive-query-hive-llap/).
> Implement shared scans with Tez
> -------------------------------
>
> Key: HIVE-16602
> URL: https://issues.apache.org/jira/browse/HIVE-16602
> Project: Hive
> Issue Type: New Feature
> Components: Physical Optimizer
> Affects Versions: 3.0.0
> Reporter: Jesus Camacho Rodriguez
> Assignee: Jesus Camacho Rodriguez
> Fix For: 3.0.0
>
> Attachments: HIVE-16602.01.patch, HIVE-16602.02.patch,
> HIVE-16602.03.patch, HIVE-16602.04.patch, HIVE-16602.patch
>
>
> Given a query plan, the goal is to identify scans on input tables that can be
> merged so the data is read only once. Optimization will be carried out at the
> physical level.
> In the longer term, identification of equivalent expressions and
> reutilization of intermediary results should be done at the logical layer via
> Spool operator.
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