[SPARK-16672] SQLBuilder should not raise exceptions on EXISTS queries

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 2.0.1, 2.1.0
• Component/s: SQL
• Assignee: Dongjoon Hyun
• Reporter: Dongjoon Hyun
• Created: 21/Jul/16 20:11
• Updated: 10/Nov/16 09:01
• Resolved: 26/Jul/16 02:52

Description

Currently, `SQLBuilder` raises `empty.reduceLeft` exceptions on *unoptimized* `EXISTS` queries. We had better prevent this.

scala> sql("CREATE TABLE t1(a int)")
scala> val df = sql("select * from t1 b where exists (select * from t1 a)")
scala> new org.apache.spark.sql.catalyst.SQLBuilder(df).toSQL
java.lang.UnsupportedOperationException: empty.reduceLeft

Issue Links

• links to: [Github] Pull Request #14307 (dongjoon-hyun)