fix codegen with UTF8String

Author: Davies Liu

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/codegen/GenerateProjection.scala

@@ -111,7 +111,8 @@ object GenerateProjection extends CodeGenerator[Seq[Expression], Projection] {
 
     val specificAccessorFunctions = NativeType.all.map { dataType =>
       val ifStatements = expressions.zipWithIndex.flatMap {
-        case (e, i) if e.dataType == dataType =>
+        // getString() is not used by expressions
+        case (e, i) if e.dataType == dataType && dataType != StringType =>
           val elementName = newTermName(s"c$i")
           // TODO: The string of ifs gets pretty inefficient as the row grows in size.
           // TODO: Optional null checks?
@@ -136,7 +137,8 @@ object GenerateProjection extends CodeGenerator[Seq[Expression], Projection] {
 
     val specificMutatorFunctions = NativeType.all.map { dataType =>
       val ifStatements = expressions.zipWithIndex.flatMap {
-        case (e, i) if e.dataType == dataType =>
+        // setString() is not used by expressions
+        case (e, i) if e.dataType == dataType && dataType != StringType =>
           val elementName = newTermName(s"c$i")
           // TODO: The string of ifs gets pretty inefficient as the row grows in size.
           // TODO: Optional null checks?

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/GeneratedMutableEvaluationSuite.scala

@@ -17,7 +17,6 @@
 
 package org.apache.spark.sql.catalyst.expressions
 
-import org.apache.spark.sql.catalyst.dsl.expressions._
 import org.apache.spark.sql.catalyst.expressions.codegen._
 
 /**
@@ -44,14 +43,6 @@ class GeneratedMutableEvaluationSuite extends ExpressionEvaluationSuite {
 
     val actual = plan(inputRow)
     val expectedRow = new GenericRow(Array[Any](expected))
-    if (actual.hashCode() != expectedRow.hashCode()) {
-      fail(
-        s"""
-          |Mismatched hashCodes for values: $actual, $expectedRow
-          |Hash Codes: ${actual.hashCode()} != ${expectedRow.hashCode()}
-          |${evaluated.code.mkString("\n")}
-        """.stripMargin)
-    }
     if (actual != expectedRow) {
       val input = if(inputRow == EmptyRow) "" else s", input: $inputRow"
       fail(s"Incorrect Evaluation: $expression, actual: $actual, expected: $expected$input")

sql/core/src/main/scala/org/apache/spark/sql/columnar/ColumnType.scala

@@ -333,7 +333,7 @@ private[sql] object STRING extends NativeColumnType(StringType, 7, 8) {
   }
 
   override def copyField(from: Row, fromOrdinal: Int, to: MutableRow, toOrdinal: Int): Unit = {
-    to.setString(toOrdinal, from.getString(fromOrdinal))
+    to.update(toOrdinal, from(fromOrdinal))
   }
 }