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From "Jacques Nadeau (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (DRILL-883) Wrong result when projecting certain columns if subquery and outer query have the same table
Date Mon, 09 Jun 2014 06:49:30 GMT

     [ https://issues.apache.org/jira/browse/DRILL-883?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Jacques Nadeau resolved DRILL-883.
----------------------------------

    Resolution: Fixed

> Wrong result when projecting certain columns if subquery and outer query have the same
table 
> ---------------------------------------------------------------------------------------------
>
>                 Key: DRILL-883
>                 URL: https://issues.apache.org/jira/browse/DRILL-883
>             Project: Apache Drill
>          Issue Type: Bug
>            Reporter: Aman Sinha
>            Assignee: Jacques Nadeau
>
> In the following query, projecting n_regionkey in the outer query produces wrong results.
 The outer query and subquery both reference nation table, although they should be separate
instances.  Note that the Scan of nation in the outer query is project the wrong column (n_nationkey
instead of n_regionkey).   That's causing the wrong results.   One other observation: disabling
the push project into scan rule gives correct results.  
> 1 row selected (0.344 seconds)
> 0: jdbc:drill:zk=local> explain plan for select n1.n_regionkey from nation n1, (select
n_nationkey from nation) as n2 where n1.n_nationkey = n2.n_nationkey;
> +------------+------------+
> |    text    |    json    |
> +------------+------------+
> | 00-00    Screen
> 00-01      UnionExchange
> 01-01        Project(n_regionkey=[$2])
> 01-02          HashJoin(condition=[=($1, $3)], joinType=[inner])
> 01-04            HashToRandomExchange(dist0=[[$1]])
> 02-01              Scan(groupscan=[ParquetGroupScan [entries=[ReadEntryWithPath [path=file:/Users/asinha/data/tpchmulti/nation]],
selectionRoot=/Users/asinha/data/tpchmulti/nation, columns=[SchemaPath [`n_nationkey`]]]])
> 01-03            Project(n_nationkey0=[$0])
> 01-05              HashToRandomExchange(dist0=[[$0]])
> 03-01                Project(n_nationkey=[$1])
> 03-02                  Scan(groupscan=[ParquetGroupScan [entries=[ReadEntryWithPath [path=file:/Users/asinha/data/tpchmulti/nation]],
selectionRoot=/Users/asinha/data/tpchmulti/nation, columns=[SchemaPath [`n_nationkey`]]]])
> 0: jdbc:drill:zk=local> select n1.n_regionkey from nation n1, (select n_nationkey
from nation) as n2 where n1.n_nationkey = n2.n_nationkey;
> +-------------+
> | n_regionkey |
> +-------------+
> | null        |
> | null        |
> | null        |
> | null        |
> | null        |
> | null        |
> | null        |
> | null        |
> | null        |
> | null        |
> | null        |
> | null        |
> | null        |
> | null        |
> | null        |
> | null        |
> | null        |
> | null        |
> | null        |
> | null        |
> | null        |
> | null        |
> | null        |
> | null        |
> | null        |
> +-------------+
> 25 rows selected (0.538 seconds)



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