[SPARK-18070][SQL] binary operator should not consider nullability when comparing input types

## What changes were proposed in this pull request?

Binary operator requires its inputs to be of same type, but it should not consider nullability, e.g. `EqualTo` should be able to compare an element-nullable array and an element-non-nullable array.

## How was this patch tested?

a regression test in `DataFrameSuite`

Author: Wenchen Fan <wenchen@databricks.com>

Closes #15606 from cloud-fan/type-bug.

2 files changed, 10 insertions, 1 deletions

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala
index fa1a2ad56c..9edc1ceff2 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Expression.scala
@@ -511,7 +511,7 @@ abstract class BinaryOperator extends BinaryExpression with ExpectsInputTypes {
 
   override def checkInputDataTypes(): TypeCheckResult = {
     // First check whether left and right have the same type, then check if the type is acceptable.
-    if (left.dataType != right.dataType) {
+    if (!left.dataType.sameType(right.dataType)) {
       TypeCheckResult.TypeCheckFailure(s"differing types in '$sql' " +
         s"(${left.dataType.simpleString} and ${right.dataType.simpleString}).")
     } else if (!inputType.acceptsType(left.dataType)) {
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/DataFrameSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/DataFrameSuite.scala
index 3fb7eeefba..33b3b78c9f 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/DataFrameSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/DataFrameSuite.scala
@@ -1649,4 +1649,13 @@ class DataFrameSuite extends QueryTest with SharedSQLContext {
     dates.except(widenTypedRows).collect()
     dates.intersect(widenTypedRows).collect()
   }
+
+  test("SPARK-18070 binary operator should not consider nullability when comparing input types") {
+    val rows = Seq(Row(Seq(1), Seq(1)))
+    val schema = new StructType()
+      .add("array1", ArrayType(IntegerType))
+      .add("array2", ArrayType(IntegerType, containsNull = false))
+    val df = spark.createDataFrame(spark.sparkContext.makeRDD(rows), schema)
+    assert(df.filter($"array1" === $"array2").count() == 1)
+  }
 }