address comment

Author: mgaido91

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

@@ -87,8 +87,6 @@ object Canonicalize {
     case Not(LessThanOrEqual(l, r)) => GreaterThan(l, r)
 
     // order the list in the In operator
-    // In subqueries contain only one element of type ListQuery. So checking that the length > 1
-    // we are not reordering In subqueries.
     case In(value, list) if list.length > 1 => In(value, list.sortBy(_.hashCode()))
 
     case _ => e

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/optimizer/OptimizeInSuite.scala

@@ -121,6 +121,21 @@ class OptimizeInSuite extends PlanTest {
     comparePlans(optimized, correctAnswer)
   }
 
+  test("OptimizedIn test: NULL IN (subquery) gets transformed to Filter(null)") {
+    val subquery = ListQuery(testRelation.select(UnresolvedAttribute("a")))
+    val originalQuery =
+      testRelation
+        .where(InSubquery(Seq(Literal.create(null, NullType)), subquery))
+        .analyze
+
+    val optimized = Optimize.execute(originalQuery.analyze)
+    val correctAnswer =
+      testRelation
+        .where(Literal.create(null, BooleanType))
+        .analyze
+    comparePlans(optimized, correctAnswer)
+  }
+
   test("OptimizedIn test: Inset optimization disabled as " +
     "list expression contains attribute)") {
     val originalQuery =

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/parser/ExpressionParserSuite.scala

@@ -155,6 +155,18 @@ class ExpressionParserSuite extends PlanTest {
     assertEqual(
       "a in (select b from c)",
       InSubquery(Seq('a), ListQuery(table("c").select('b))))
+
+    assertEqual(
+      "(a, b, c) in (select d, e, f from g)",
+      InSubquery(Seq('a, 'b, 'c), ListQuery(table("g").select('d, 'e, 'f))))
+
+    assertEqual(
+      "(a, b) in (select c from d)",
+      InSubquery(Seq('a, 'b), ListQuery(table("d").select('c))))
+
+    assertEqual(
+      "(a) in (select b from c)",
+      InSubquery(Seq('a), ListQuery(table("c").select('b))))
   }
 
   test("like expressions") {