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From "He Yongqiang (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HIVE-153) explain should give meaningful column names
Date Wed, 20 May 2009 17:19:45 GMT

    [ https://issues.apache.org/jira/browse/HIVE-153?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12711241#action_12711241
] 

He Yongqiang commented on HIVE-153:
-----------------------------------

How about this?
{noformat}
hive> explain FROM a SELECT a.country as b, count(1) as c WHERE a.ds='2008-12-09' GROUP
BY a.country;     OK
...

STAGE DEPENDENCIES:
  Stage-1 is a root stage
  Stage-0 is a root stage

STAGE PLANS:
  Stage: Stage-1
    Map Reduce
      Alias -> Map Operator Tree:
        a 
            Filter Operator
              predicate:
                  expr: (ds = '2008-12-09')
                  type: boolean
              Group By Operator
                aggregations:
                      expr: count(1)
                keys:
                      expr: country
                      type: string
                mode: hash
                Reduce Output Operator
                  key expressions:
                        expr: country
                        type: string
                  sort order: +
                  Map-reduce partition columns:
                        expr: country
                        type: string
                  tag: -1
                  value expressions:
                        expr: 1
                        type: bigint
      Reduce Operator Tree:
        Group By Operator
          aggregations:
                expr: count(VALUE.0)
          keys:
                expr: KEY.0
                type: string
          mode: mergepartial
          Select Operator
            expressions:
                  expr: KEY.0
                  type: string
                  expr: 1
                  type: bigint
            File Output Operator
              compressed: true
              GlobalTableId: 0
              table:
                  input format: org.apache.hadoop.mapred.TextInputFormat
                  output format: org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat

  Stage: Stage-0
    Fetch Operator
      limit: -1

{noformat}

> explain should give meaningful column names
> -------------------------------------------
>
>                 Key: HIVE-153
>                 URL: https://issues.apache.org/jira/browse/HIVE-153
>             Project: Hadoop Hive
>          Issue Type: Improvement
>          Components: Query Processor
>            Reporter: Zheng Shao
>
> Currently explain uses numbers like "1" to represent the columns.
> It will be much better to print out the real name of the columns.
> hive> explain FROM table a SELECT a.country as b, count(1) as c WHERE a.ds='2008-12-09'
GROUP BY a.country;
> ...
>             Select Operator
>               expressions:
>                     expr: country
>                     type: string
>                     expr: ds
>                     type: string
>               Filter Operator
>                 predicate:
>                     expr: (1 = '2008-12-09')
>                     type: boolean
>                 Reduce Output Operator
>                   key expressions:
>                         expr: 0
>                         type: string
>                   sort order: +
>                   Map-reduce partition columns:
>                         expr: rand()
>                         type: double
>                   tag: -1
>                   value expressions:
>                         expr: 1
>                         type: int

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