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From "Dongjoon Hyun (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (SPARK-17114) Adding a 'GROUP BY 1' where first column is literal results in wrong answer
Date Thu, 08 Dec 2016 22:54:58 GMT

     [ https://issues.apache.org/jira/browse/SPARK-17114?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Dongjoon Hyun updated SPARK-17114:
----------------------------------
    Component/s: SQL

> Adding a 'GROUP BY 1' where first column is literal results in wrong answer
> ---------------------------------------------------------------------------
>
>                 Key: SPARK-17114
>                 URL: https://issues.apache.org/jira/browse/SPARK-17114
>             Project: Spark
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 1.6.2, 2.0.0
>            Reporter: Josh Rosen
>            Assignee: Herman van Hovell
>              Labels: correctness
>             Fix For: 2.0.1, 2.1.0
>
>
> Consider the following example:
> {code}
> sc.parallelize(Seq(128, 256)).toDF("int_col").registerTempTable("mytable")
> // The following query should return an empty result set because the `IN` filter condition
is always false for this single-row table.
> val withoutGroupBy = sqlContext.sql("""
>   SELECT 'foo'
>   FROM mytable
>   WHERE int_col == 0
> """)
> assert(withoutGroupBy.collect().isEmpty, "original query returned wrong answer")
> // After adding a 'GROUP BY 1' the query result should still be empty because we'd be
grouping an empty table:
> val withGroupBy = sqlContext.sql("""
>   SELECT 'foo'
>   FROM mytable
>   WHERE int_col == 0
>   GROUP BY 1
> """)
> assert(withGroupBy.collect().isEmpty, "adding GROUP BY resulted in wrong answer")
> {code}
> Here, this fails the second assertion by returning a single row. It appears that running
{{group by 1}} where column 1 is a constant causes filter conditions to be ignored.
> Both PostgreSQL and SQLite return empty result sets for the query containing the {{GROUP
BY}}. 



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