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Posted to issues@spark.apache.org by "Nattavut Sutyanyong (JIRA)" <ji...@apache.org> on 2016/07/29 21:38:20 UTC

[jira] [Created] (SPARK-16804) Correlated subqueries containing LIMIT return incorrect results

Nattavut Sutyanyong created SPARK-16804:
-------------------------------------------

             Summary: Correlated subqueries containing LIMIT return incorrect results
                 Key: SPARK-16804
                 URL: https://issues.apache.org/jira/browse/SPARK-16804
             Project: Spark
          Issue Type: Bug
          Components: SQL
    Affects Versions: 2.0.0
            Reporter: Nattavut Sutyanyong


Correlated subqueries with LIMIT could return incorrect results. The rule ResolveSubquery in the Analysis phase moves correlated predicates to a join predicates and neglect the semantic of the LIMIT.

Example:

Seq(1, 2).toDF("c1").createOrReplaceTempView("t1")
Seq(1, 2).toDF("c2").createOrReplaceTempView("t2")

sql("select c1 from t1 where exists (select 1 from t2 where t1.c1=t2.c2 LIMIT 1)").show
+---+                                                                           
| c1|
+---+
|  1|
+---+

The correct result contains both rows from T1.



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