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https://issues.apache.org/jira/browse/SPARK-17114?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Apache Spark reassigned SPARK-17114:
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Assignee: (was: Apache Spark)
> 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
> Affects Versions: 1.6.2, 2.0.0
> Reporter: Josh Rosen
> Labels: correctness
>
> 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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