[SPARK-7229] [SQL] SpecificMutableRow should take integer type as internal representation for Date

Author: Cheng Hao <hao.cheng@intel.com>

Closes #5772 from chenghao-intel/specific_row and squashes the following commits:

2cd064d [Cheng Hao] scala style issue
60347a2 [Cheng Hao] SpecificMutableRow should take integer type as internal representation for DateType

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

@@ -202,6 +202,7 @@ final class SpecificMutableRow(val values: Array[MutableValue]) extends MutableR
         case DoubleType => new MutableDouble
         case BooleanType => new MutableBoolean
         case LongType => new MutableLong
+        case DateType => new MutableInt // We use INT for DATE internally
         case _ => new MutableAny
       }.toArray)
 

sql/core/src/test/scala/org/apache/spark/sql/jdbc/JDBCSuite.scala

@@ -256,6 +256,15 @@ class JDBCSuite extends FunSuite with BeforeAndAfter {
     assert(cachedRows(0).getAs[java.sql.Date](1) === java.sql.Date.valueOf("1996-01-01"))
   }
 
+  test("test DATE types in cache") {
+    val rows = TestSQLContext.jdbc(urlWithUserAndPass, "TEST.TIMETYPES").collect()
+    TestSQLContext
+      .jdbc(urlWithUserAndPass, "TEST.TIMETYPES").cache().registerTempTable("mycached_date")
+    val cachedRows = sql("select * from mycached_date").collect()
+    assert(rows(0).getAs[java.sql.Date](1) === java.sql.Date.valueOf("1996-01-01"))
+    assert(cachedRows(0).getAs[java.sql.Date](1) === java.sql.Date.valueOf("1996-01-01"))
+  }
+
   test("H2 floating-point types") {
     val rows = sql("SELECT * FROM flttypes").collect()
     assert(rows(0).getDouble(0) === 1.00000000000000022) // Yes, I meant ==.