[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, 16 insertions, 0 deletions

diff --git a/sql/core/src/test/scala/org/apache/spark/sql/DataFrameFunctionsSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/DataFrameFunctionsSuite.scala
index 73d77651a0..0f6c49e759 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/DataFrameFunctionsSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/DataFrameFunctionsSuite.scala
@@ -352,6 +352,22 @@ class DataFrameFunctionsSuite extends QueryTest with SharedSQLContext {
     )
   }
 
+  test("map_keys/map_values function") {
+    val df = Seq(
+      (Map[Int, Int](1 -> 100, 2 -> 200), "x"),
+      (Map[Int, Int](), "y"),
+      (Map[Int, Int](1 -> 100, 2 -> 200, 3 -> 300), "z")
+    ).toDF("a", "b")
+    checkAnswer(
+      df.selectExpr("map_keys(a)"),
+      Seq(Row(Seq(1, 2)), Row(Seq.empty), Row(Seq(1, 2, 3)))
+    )
+    checkAnswer(
+      df.selectExpr("map_values(a)"),
+      Seq(Row(Seq(100, 200)), Row(Seq.empty), Row(Seq(100, 200, 300)))
+    )
+  }
+
   test("array contains function") {
     val df = Seq(
       (Seq[Int](1, 2), "x"),