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From "Phabricator (Updated) (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HIVE-2566) reduce the number map-reduce jobs for union all
Date Fri, 11 Nov 2011 02:32:53 GMT

     [ https://issues.apache.org/jira/browse/HIVE-2566?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Phabricator updated HIVE-2566:
------------------------------

    Attachment: HIVE-2566.D405.1.patch

njain requested code review of "HIVE-2566 [jira] reduce the number map-reduce jobs for union
all".
Reviewers: JIRA

  HIVE-2566: initial patch

  A query like:

  select s.key, s.value from (
  select key, value from src2  where key < 10
  union all
  select key, value from src3  where key < 10
  union all
  select key, value from src4  where key < 10
  union all
  select key, count(1) as value from src5 group by key
  )s;

  should run the last sub-query
  'select key, count(1) as value from src5 group by key'
  as a map-reduce job.

  And then the union should be a map-only job reading from the first 3 map-only subqueries
  and the output of the last map-reduce job.

  The current plan is very inefficient.

TEST PLAN
  EMPTY

REVISION DETAIL
  https://reviews.facebook.net/D405

AFFECTED FILES
  ql/src/test/results/clientpositive/union24.q.out
  ql/src/test/queries/clientpositive/union24.q
  ql/src/java/org/apache/hadoop/hive/ql/optimizer/GenMRProcContext.java
  ql/src/java/org/apache/hadoop/hive/ql/optimizer/GenMRUnion1.java
  ql/src/java/org/apache/hadoop/hive/ql/optimizer/GenMapRedUtils.java
  ql/src/java/org/apache/hadoop/hive/ql/exec/Operator.java

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> reduce the number map-reduce jobs for union all
> -----------------------------------------------
>
>                 Key: HIVE-2566
>                 URL: https://issues.apache.org/jira/browse/HIVE-2566
>             Project: Hive
>          Issue Type: Improvement
>            Reporter: Namit Jain
>            Assignee: Namit Jain
>         Attachments: HIVE-2566.D405.1.patch
>
>
> A query like:
> select s.key, s.value from (
>   select key, value from src2  where key < 10
>   union all 
>   select key, value from src3  where key < 10
>   union all 
>   select key, value from src4  where key < 10
>   union all 
>   select key, count(1) as value from src5 group by key
> )s;
> should run the last sub-query 
> 'select key, count(1) as value from src5 group by key'
> as a map-reduce job.
> And then the union should be a map-only job reading from the first 3 map-only subqueries
> and the output of the last map-reduce job.
> The current plan is very inefficient.

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