[SPARK-16278][SPARK-16279][SQL] Implement map_keys/map_values SQL functions

## What changes were proposed in this pull request?

This PR adds `map_keys` and `map_values` SQL functions in order to remove Hive fallback.

## How was this patch tested?

Pass the Jenkins tests including new testcases.

Author: Dongjoon Hyun <dongjoon@apache.org>

Closes #13967 from dongjoon-hyun/SPARK-16278.

1 files changed, 13 insertions, 0 deletions

diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/CollectionFunctionsSuite.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/CollectionFunctionsSuite.scala
index 1aae4678d6..a5f784fdcc 100644
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/CollectionFunctionsSuite.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/CollectionFunctionsSuite.scala
@@ -44,6 +44,19 @@ class CollectionFunctionsSuite extends SparkFunSuite with ExpressionEvalHelper {
     checkEvaluation(Literal.create(null, ArrayType(StringType)), null)
   }
 
+  test("MapKeys/MapValues") {
+    val m0 = Literal.create(Map("a" -> "1", "b" -> "2"), MapType(StringType, StringType))
+    val m1 = Literal.create(Map[String, String](), MapType(StringType, StringType))
+    val m2 = Literal.create(null, MapType(StringType, StringType))
+
+    checkEvaluation(MapKeys(m0), Seq("a", "b"))
+    checkEvaluation(MapValues(m0), Seq("1", "2"))
+    checkEvaluation(MapKeys(m1), Seq())
+    checkEvaluation(MapValues(m1), Seq())
+    checkEvaluation(MapKeys(m2), null)
+    checkEvaluation(MapValues(m2), null)
+  }
+
   test("Sort Array") {
     val a0 = Literal.create(Seq(2, 1, 3), ArrayType(IntegerType))
     val a1 = Literal.create(Seq[Integer](), ArrayType(IntegerType))