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From "Phabricator (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-3562) Some limit can be pushed down to map stage
Date Wed, 10 Oct 2012 05:21:03 GMT

     [ https://issues.apache.org/jira/browse/HIVE-3562?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Phabricator updated HIVE-3562:
------------------------------

    Attachment: HIVE-3562.D5967.1.patch

navis requested code review of "HIVE-3562 [jira] Some limit can be pushed down to map stage".
Reviewers: JIRA

  DPAL-1910 Some limit can be pushed down to map stage

  Queries with limit clause (with reasonable number), for example

  select * from src order by key limit 10;

  makes operator tree,
  TS-SEL-RS-EXT-LIMIT-FS

  But LIMIT can be partially calculated in RS, reducing size of shuffling.
  TS-SEL-RS(TOP-N)-EXT-LIMIT-FS

TEST PLAN
  EMPTY

REVISION DETAIL
  https://reviews.facebook.net/D5967

AFFECTED FILES
  common/src/java/org/apache/hadoop/hive/conf/HiveConf.java
  ql/src/java/org/apache/hadoop/hive/ql/exec/ReduceSinkOperator.java
  ql/src/java/org/apache/hadoop/hive/ql/optimizer/LimitPushdownOptimizer.java
  ql/src/java/org/apache/hadoop/hive/ql/optimizer/Optimizer.java
  ql/src/java/org/apache/hadoop/hive/ql/plan/ReduceSinkDesc.java
  ql/src/test/queries/clientpositive/limit_pushdown.q
  ql/src/test/results/clientpositive/limit_pushdown.q.out

MANAGE HERALD DIFFERENTIAL RULES
  https://reviews.facebook.net/herald/view/differential/

WHY DID I GET THIS EMAIL?
  https://reviews.facebook.net/herald/transcript/14199/

To: JIRA, navis

                
> Some limit can be pushed down to map stage
> ------------------------------------------
>
>                 Key: HIVE-3562
>                 URL: https://issues.apache.org/jira/browse/HIVE-3562
>             Project: Hive
>          Issue Type: Bug
>            Reporter: Navis
>            Assignee: Navis
>            Priority: Trivial
>         Attachments: HIVE-3562.D5967.1.patch
>
>
> Queries with limit clause (with reasonable number), for example
> {noformat}
> select * from src order by key limit 10;
> {noformat}
> makes operator tree, 
> TS-SEL-RS-EXT-LIMIT-FS
> But LIMIT can be partially calculated in RS, reducing size of shuffling.
> TS-SEL-RS(TOP-N)-EXT-LIMIT-FS

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