[SPARK-16804] Correlated subqueries containing non-deterministic operators return incorrect results

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0.0
• Fix Version/s: 2.0.2, 2.1.0
• Component/s: SQL
• Target Version/s: 2.0.1, 2.1.0
• Assignee: Nattavut Sutyanyong
• Reporter: Nattavut Sutyanyong
• Created: 29/Jul/16 21:37
• Updated: 15/Nov/16 22:22
• Resolved: 08/Aug/16 10:16

Description

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.

Issue Links

• relates to: SPARK-18455 General support for correlated subquery processing
• links to: [Github] Pull Request #14411 (nsyca)
• links to: [Github] Pull Request #15772 (hvanhovell)