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From "Phabricator (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-3972) Support using multiple reducer for fetching order by results
Date Mon, 25 Feb 2013 04:38:13 GMT

     [ https://issues.apache.org/jira/browse/HIVE-3972?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Phabricator updated HIVE-3972:
------------------------------

    Attachment: HIVE-3972.D8349.4.patch

navis updated the revision "HIVE-3972 [jira] Support using multiple reducer for fetching order
by results".

  Rebased to trunk

Reviewers: JIRA

REVISION DETAIL
  https://reviews.facebook.net/D8349

CHANGE SINCE LAST DIFF
  https://reviews.facebook.net/D8349?vs=27303&id=28557#toc

AFFECTED FILES
  common/src/java/org/apache/hadoop/hive/conf/HiveConf.java
  conf/hive-default.xml.template
  ql/src/java/org/apache/hadoop/hive/ql/exec/FetchOperator.java
  ql/src/java/org/apache/hadoop/hive/ql/exec/FetchTask.java
  ql/src/java/org/apache/hadoop/hive/ql/exec/MergeSortingFetcher.java
  ql/src/java/org/apache/hadoop/hive/ql/exec/RowFetcher.java
  ql/src/java/org/apache/hadoop/hive/ql/exec/SMBMapJoinOperator.java
  ql/src/java/org/apache/hadoop/hive/ql/parse/QB.java
  ql/src/java/org/apache/hadoop/hive/ql/parse/SemanticAnalyzer.java
  ql/src/java/org/apache/hadoop/hive/ql/plan/FetchWork.java
  ql/src/test/queries/clientpositive/orderby_query_bucketing.q
  ql/src/test/results/clientpositive/orderby_query_bucketing.q.out

To: JIRA, navis
Cc: njain

                
> Support using multiple reducer for fetching order by results
> ------------------------------------------------------------
>
>                 Key: HIVE-3972
>                 URL: https://issues.apache.org/jira/browse/HIVE-3972
>             Project: Hive
>          Issue Type: Improvement
>          Components: Query Processor
>            Reporter: Navis
>            Assignee: Navis
>            Priority: Minor
>         Attachments: HIVE-3972.D8349.1.patch, HIVE-3972.D8349.2.patch, HIVE-3972.D8349.3.patch,
HIVE-3972.D8349.4.patch
>
>
> Queries for fetching results which have lastly "order by" clause make final MR run with
single reducer, which can be too much. For example, 
> {code}
> select value, sum(key) as sum from src group by value order by sum;
> {code}
> If number of reducer is reasonable, multiple result files could be merged into single
sorted stream in the fetcher level.

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