[SPARK-20175][SQL] Exists should not be evaluated in Join operator

## What changes were proposed in this pull request?

Similar to `ListQuery`, `Exists` should not be evaluated in `Join` operator too.

## How was this patch tested?

Jenkins tests.

Please review http://spark.apache.org/contributing.html before opening a pull request.

Author: Liang-Chi Hsieh <[email protected]>

Closes #17491 from viirya/dont-push-exists-to-join.

Author: viirya

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/predicates.scala

@@ -92,11 +92,12 @@ trait PredicateHelper {
   protected def canEvaluateWithinJoin(expr: Expression): Boolean = expr match {
     // Non-deterministic expressions are not allowed as join conditions.
     case e if !e.deterministic => false
-    case l: ListQuery =>
+    case _: ListQuery | _: Exists =>
       // A ListQuery defines the query which we want to search in an IN subquery expression.
       // Currently the only way to evaluate an IN subquery is to convert it to a
       // LeftSemi/LeftAnti/ExistenceJoin by `RewritePredicateSubquery` rule.
       // It cannot be evaluated as part of a Join operator.
+      // An Exists shouldn't be push into a Join operator too.
       false
     case e: SubqueryExpression =>
       // non-correlated subquery will be replaced as literal

sql/core/src/test/scala/org/apache/spark/sql/SubquerySuite.scala

@@ -844,4 +844,14 @@ class SubquerySuite extends QueryTest with SharedSQLContext {
         Row(0) :: Row(1) :: Nil)
     }
   }
+
+  test("ListQuery and Exists should work even no correlated references") {
+    checkAnswer(
+      sql("select * from l, r where l.a = r.c AND (r.d in (select d from r) OR l.a >= 1)"),
+      Row(2, 1.0, 2, 3.0) :: Row(2, 1.0, 2, 3.0) :: Row(2, 1.0, 2, 3.0) ::
+        Row(2, 1.0, 2, 3.0) :: Row(3.0, 3.0, 3, 2.0) :: Row(6, null, 6, null) :: Nil)
+    checkAnswer(
+      sql("select * from l, r where l.a = r.c + 1 AND (exists (select * from r) OR l.a = r.c)"),
+      Row(3, 3.0, 2, 3.0) :: Row(3, 3.0, 2, 3.0) :: Nil)
+  }
 }