code review, minor updates, and rearrange imports.

sql/catalyst/src/main/scala/org/apache/spark/sql/types/dataTypes.scala

@@ -719,7 +719,7 @@ object StructType {
  * // twoFields: StructType =
  * //   StructType(List(StructField(b,LongType,false), StructField(c,BooleanType,false)))
  *
- * // Those names do not have matching fields will be ignored.
+ * // Any names without matching fields will be ignored.
  * // For the case shown below, "d" will be ignored and
  * // it is treated as struct(Set("b", "c")).
  * val ignoreNonExisting = struct(Set("b", "c", "d"))
@@ -766,8 +766,8 @@ case class StructType(fields: Array[StructField]) extends DataType with Seq[Stru
   }
 
   /**
-   * Returns a [[StructType]] containing [[StructField]]s of the given names.
-   * Those names which do not have matching fields will be ignored.
+   * Returns a [[StructType]] containing [[StructField]]s of the given names, preserving the
+   * original order of fields. Those names which do not have matching fields will be ignored.
    */
   def apply(names: Set[String]): StructType = {
     val nonExistFields = names -- fieldNamesSet
@@ -779,8 +779,8 @@ case class StructType(fields: Array[StructField]) extends DataType with Seq[Stru
     StructType(fields.filter(f => names.contains(f.name)))
   }
 
-  protected[sql] def toAttributes =
-    fields.map(f => AttributeReference(f.name, f.dataType, f.nullable, f.metadata)())
+  protected[sql] def toAttributes: Seq[AttributeReference] =
+    map(f => AttributeReference(f.name, f.dataType, f.nullable, f.metadata)())
 
   def treeString: String = {
     val builder = new StringBuilder
@@ -799,7 +799,7 @@ case class StructType(fields: Array[StructField]) extends DataType with Seq[Stru
 
   override private[sql] def jsonValue =
     ("type" -> typeName) ~
-      ("fields" -> fields.map(_.jsonValue).toSeq)
+      ("fields" -> map(_.jsonValue))
 
   override def apply(fieldIndex: Int): StructField = fields(fieldIndex)
 

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

@@ -21,17 +21,15 @@ import java.sql.{Date, Timestamp}
 
 import scala.collection.immutable.HashSet
 
-import org.apache.spark.sql.types.decimal.Decimal
+import org.scalactic.TripleEqualsSupport.Spread
 import org.scalatest.FunSuite
 import org.scalatest.Matchers._
-import org.scalactic.TripleEqualsSupport.Spread
 
+import org.apache.spark.sql.catalyst.dsl.expressions._
 import org.apache.spark.sql.types._
+import org.apache.spark.sql.types.decimal.Decimal
 
 
-/* Implicit conversions */
-import org.apache.spark.sql.catalyst.dsl.expressions._
-
 class ExpressionEvaluationSuite extends FunSuite {
 
   test("literals") {

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/util/MetadataSuite.scala

@@ -17,10 +17,11 @@
 
 package org.apache.spark.sql.catalyst.util
 
-import org.apache.spark.sql.types.{MetadataBuilder, Metadata}
 import org.json4s.jackson.JsonMethods.parse
 import org.scalatest.FunSuite
 
+import org.apache.spark.sql.types.{MetadataBuilder, Metadata}
+
 class MetadataSuite extends FunSuite {
 
   val baseMetadata = new MetadataBuilder()

sql/core/src/main/scala/org/apache/spark/sql/SQLContext.scala

@@ -21,23 +21,21 @@ import scala.language.implicitConversions
 import scala.reflect.runtime.universe.TypeTag
 
 import org.apache.hadoop.conf.Configuration
-
 import org.apache.spark.SparkContext
 import org.apache.spark.annotation.{AlphaComponent, DeveloperApi, Experimental}
 import org.apache.spark.rdd.RDD
 import org.apache.spark.sql.catalyst.ScalaReflection
 import org.apache.spark.sql.catalyst.analysis._
 import org.apache.spark.sql.catalyst.dsl.ExpressionConversions
 import org.apache.spark.sql.catalyst.expressions._
-import org.apache.spark.sql.catalyst.optimizer.{Optimizer, DefaultOptimizer}
+import org.apache.spark.sql.catalyst.optimizer.{DefaultOptimizer, Optimizer}
 import org.apache.spark.sql.catalyst.plans.logical.LogicalPlan
 import org.apache.spark.sql.catalyst.rules.RuleExecutor
-import org.apache.spark.sql.types.UserDefinedType
-import org.apache.spark.sql.execution.{SparkStrategies, _}
+import org.apache.spark.sql.execution._
 import org.apache.spark.sql.json._
-import org.apache.spark.sql.types._
 import org.apache.spark.sql.parquet.ParquetRelation
-import org.apache.spark.sql.sources.{DataSourceStrategy, BaseRelation, DDLParser, LogicalRelation}
+import org.apache.spark.sql.sources.{BaseRelation, DDLParser, DataSourceStrategy, LogicalRelation}
+import org.apache.spark.sql.types._
 
 /**
  * :: AlphaComponent ::

sql/core/src/main/scala/org/apache/spark/sql/api/java/JavaSchemaRDD.scala

@@ -20,12 +20,12 @@ package org.apache.spark.sql.api.java
 import java.util.{List => JList}
 
 import org.apache.spark.Partitioner
-import org.apache.spark.api.java.{JavaRDDLike, JavaRDD}
+import org.apache.spark.api.java.{JavaRDD, JavaRDDLike}
 import org.apache.spark.api.java.function.{Function => JFunction}
 import org.apache.spark.rdd.RDD
-import org.apache.spark.sql.types.StructType
 import org.apache.spark.sql.{SQLContext, SchemaRDD, SchemaRDDLike}
 import org.apache.spark.sql.catalyst.plans.logical.LogicalPlan
+import org.apache.spark.sql.types.StructType
 import org.apache.spark.storage.StorageLevel
 
 /**

sql/core/src/main/scala/org/apache/spark/sql/api/java/Row.scala

@@ -17,8 +17,6 @@
 
 package org.apache.spark.sql.api.java
 
-import org.apache.spark.sql.types.decimal.Decimal
-
 import scala.annotation.varargs
 import scala.collection.convert.Wrappers.{JListWrapper, JMapWrapper}
 import scala.collection.JavaConversions

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

@@ -17,11 +17,11 @@
 
 package org.apache.spark.sql.columnar
 
-import java.nio.{ByteOrder, ByteBuffer}
+import java.nio.{ByteBuffer, ByteOrder}
 
-import org.apache.spark.sql.types.{BinaryType, NativeType, DataType}
 import org.apache.spark.sql.catalyst.expressions.MutableRow
 import org.apache.spark.sql.columnar.compression.CompressibleColumnAccessor
+import org.apache.spark.sql.types.{BinaryType, DataType, NativeType}
 
 /**
  * An `Iterator` like trait used to extract values from columnar byte buffer. When a value is

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

@@ -20,9 +20,9 @@ package org.apache.spark.sql.columnar
 import java.nio.{ByteBuffer, ByteOrder}
 
 import org.apache.spark.sql.Row
-import org.apache.spark.sql.types._
 import org.apache.spark.sql.columnar.ColumnBuilder._
 import org.apache.spark.sql.columnar.compression.{AllCompressionSchemes, CompressibleColumnBuilder}
+import org.apache.spark.sql.types._
 
 private[sql] trait ColumnBuilder {
   /**

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

@@ -24,8 +24,8 @@ import scala.reflect.runtime.universe.TypeTag
 
 import org.apache.spark.sql.Row
 import org.apache.spark.sql.catalyst.expressions.MutableRow
-import org.apache.spark.sql.types._
 import org.apache.spark.sql.execution.SparkSqlSerializer
+import org.apache.spark.sql.types._
 
 /**
  * An abstract class that represents type of a column. Used to append/extract Java objects into/from

sql/core/src/main/scala/org/apache/spark/sql/columnar/compression/CompressibleColumnAccessor.scala

@@ -18,8 +18,8 @@
 package org.apache.spark.sql.columnar.compression
 
 import org.apache.spark.sql.catalyst.expressions.MutableRow
-import org.apache.spark.sql.types.NativeType
 import org.apache.spark.sql.columnar.{ColumnAccessor, NativeColumnAccessor}
+import org.apache.spark.sql.types.NativeType
 
 private[sql] trait CompressibleColumnAccessor[T <: NativeType] extends ColumnAccessor {
   this: NativeColumnAccessor[T] =>

sql/core/src/main/scala/org/apache/spark/sql/columnar/compression/CompressibleColumnBuilder.scala

@@ -21,8 +21,8 @@ import java.nio.{ByteBuffer, ByteOrder}
 
 import org.apache.spark.Logging
 import org.apache.spark.sql.Row
-import org.apache.spark.sql.types.NativeType
 import org.apache.spark.sql.columnar.{ColumnBuilder, NativeColumnBuilder}
+import org.apache.spark.sql.types.NativeType
 
 /**
  * A stackable trait that builds optionally compressed byte buffer for a column.  Memory layout of

sql/core/src/main/scala/org/apache/spark/sql/columnar/compression/CompressionScheme.scala

@@ -21,8 +21,8 @@ import java.nio.{ByteBuffer, ByteOrder}
 
 import org.apache.spark.sql.Row
 import org.apache.spark.sql.catalyst.expressions.MutableRow
-import org.apache.spark.sql.types.NativeType
 import org.apache.spark.sql.columnar.{ColumnType, NativeColumnType}
+import org.apache.spark.sql.types.NativeType
 
 private[sql] trait Encoder[T <: NativeType] {
   def gatherCompressibilityStats(row: Row, ordinal: Int): Unit = {}

sql/core/src/main/scala/org/apache/spark/sql/columnar/compression/compressionSchemes.scala

@@ -25,10 +25,11 @@ import scala.reflect.runtime.universe.runtimeMirror
 
 import org.apache.spark.sql.Row
 import org.apache.spark.sql.catalyst.expressions.{MutableRow, SpecificMutableRow}
-import org.apache.spark.sql.types._
 import org.apache.spark.sql.columnar._
+import org.apache.spark.sql.types._
 import org.apache.spark.util.Utils
 
+
 private[sql] case object PassThrough extends CompressionScheme {
   override val typeId = 0
 

sql/core/src/main/scala/org/apache/spark/sql/execution/SparkStrategies.scala

@@ -17,15 +17,15 @@
 
 package org.apache.spark.sql.execution
 
-import org.apache.spark.sql.{SQLContext, Strategy, execution}
 import org.apache.spark.sql.catalyst.expressions._
 import org.apache.spark.sql.catalyst.planning._
 import org.apache.spark.sql.catalyst.plans._
 import org.apache.spark.sql.catalyst.plans.logical.LogicalPlan
 import org.apache.spark.sql.catalyst.plans.physical._
-import org.apache.spark.sql.types._
-import org.apache.spark.sql.columnar.{InMemoryRelation, InMemoryColumnarTableScan}
+import org.apache.spark.sql.columnar.{InMemoryColumnarTableScan, InMemoryRelation}
 import org.apache.spark.sql.parquet._
+import org.apache.spark.sql.types._
+import org.apache.spark.sql.{SQLContext, Strategy, execution}
 
 
 private[sql] abstract class SparkStrategies extends QueryPlanner[SparkPlan] {

sql/core/src/main/scala/org/apache/spark/sql/execution/pythonUdfs.scala

@@ -19,8 +19,6 @@ package org.apache.spark.sql.execution
 
 import java.util.{List => JList, Map => JMap}
 
-import org.apache.spark.sql.types.decimal.Decimal
-
 import scala.collection.JavaConversions._
 import scala.collection.JavaConverters._
 

sql/core/src/main/scala/org/apache/spark/sql/parquet/ParquetConverter.scala

@@ -17,16 +17,15 @@
 
 package org.apache.spark.sql.parquet
 
-import org.apache.spark.sql.types.decimal.Decimal
-
 import scala.collection.mutable.{Buffer, ArrayBuffer, HashMap}
 
 import parquet.io.api.{PrimitiveConverter, GroupConverter, Binary, Converter}
 import parquet.schema.MessageType
 
-import org.apache.spark.sql.types._
 import org.apache.spark.sql.catalyst.expressions._
 import org.apache.spark.sql.parquet.CatalystConverter.FieldType
+import org.apache.spark.sql.types._
+import org.apache.spark.sql.types.decimal.Decimal
 
 /**
  * Collection of converters of Parquet types (group and primitive types) that

sql/core/src/main/scala/org/apache/spark/sql/parquet/newParquet.scala

@@ -18,25 +18,24 @@ package org.apache.spark.sql.parquet
 
 import java.util.{List => JList}
 
+import scala.collection.JavaConversions._
+
 import org.apache.hadoop.fs.{FileStatus, FileSystem, Path}
 import org.apache.hadoop.conf.{Configurable, Configuration}
 import org.apache.hadoop.io.Writable
 import org.apache.hadoop.mapreduce.{JobContext, InputSplit, Job}
-import org.apache.spark.sql.catalyst.expressions.codegen.GeneratePredicate
 
 import parquet.hadoop.ParquetInputFormat
 import parquet.hadoop.util.ContextUtil
 
 import org.apache.spark.annotation.DeveloperApi
 import org.apache.spark.{Partition => SparkPartition, Logging}
 import org.apache.spark.rdd.{NewHadoopPartition, RDD}
-
 import org.apache.spark.sql.{SQLConf, Row, SQLContext}
 import org.apache.spark.sql.catalyst.expressions._
-import org.apache.spark.sql.types.{StringType, IntegerType, StructField, StructType}
 import org.apache.spark.sql.sources._
+import org.apache.spark.sql.types.{IntegerType, StructField, StructType}
 
-import scala.collection.JavaConversions._
 
 /**
  * Allows creation of parquet based tables using the syntax

sql/core/src/main/scala/org/apache/spark/sql/sources/LogicalRelation.scala

@@ -27,7 +27,7 @@ private[sql] case class LogicalRelation(relation: BaseRelation)
   extends LeafNode
   with MultiInstanceRelation {
 
-  override val output: Seq[AttributeReference] = relation.schema.toAttributes.toSeq
+  override val output: Seq[AttributeReference] = relation.schema.toAttributes
 
   // Logical Relations are distinct if they have different output for the sake of transformations.
   override def equals(other: Any) = other match {

sql/core/src/test/scala/org/apache/spark/sql/ScalaReflectionRelationSuite.scala

@@ -19,7 +19,6 @@ package org.apache.spark.sql
 
 import java.sql.{Date, Timestamp}
 
-import org.apache.spark.sql.types.decimal.Decimal
 import org.scalatest.FunSuite
 
 import org.apache.spark.sql.catalyst.expressions._

sql/core/src/test/scala/org/apache/spark/sql/UserDefinedTypeSuite.scala

@@ -20,8 +20,8 @@ package org.apache.spark.sql
 import scala.beans.{BeanInfo, BeanProperty}
 
 import org.apache.spark.rdd.RDD
-import org.apache.spark.sql.types._
 import org.apache.spark.sql.test.TestSQLContext._
+import org.apache.spark.sql.types._
 
 @SQLUserDefinedType(udt = classOf[MyDenseVectorUDT])
 private[sql] class MyDenseVector(val data: Array[Double]) extends Serializable {

sql/core/src/test/scala/org/apache/spark/sql/columnar/ColumnTypeSuite.scala

@@ -24,9 +24,9 @@ import org.scalatest.FunSuite
 
 import org.apache.spark.Logging
 import org.apache.spark.sql.catalyst.expressions.GenericMutableRow
-import org.apache.spark.sql.types._
 import org.apache.spark.sql.columnar.ColumnarTestUtils._
 import org.apache.spark.sql.execution.SparkSqlSerializer
+import org.apache.spark.sql.types._
 
 class ColumnTypeSuite extends FunSuite with Logging {
   val DEFAULT_BUFFER_SIZE = 512

sql/core/src/test/scala/org/apache/spark/sql/columnar/NullableColumnBuilderSuite.scala

@@ -19,8 +19,8 @@ package org.apache.spark.sql.columnar
 
 import org.scalatest.FunSuite
 
-import org.apache.spark.sql.types._
 import org.apache.spark.sql.execution.SparkSqlSerializer
+import org.apache.spark.sql.types._
 
 class TestNullableColumnBuilder[T <: DataType, JvmType](columnType: ColumnType[T, JvmType])
   extends BasicColumnBuilder[T, JvmType](new NoopColumnStats, columnType)

sql/core/src/test/scala/org/apache/spark/sql/columnar/compression/DictionaryEncodingSuite.scala

@@ -22,9 +22,9 @@ import java.nio.ByteBuffer
 import org.scalatest.FunSuite
 
 import org.apache.spark.sql.catalyst.expressions.GenericMutableRow
-import org.apache.spark.sql.types.NativeType
 import org.apache.spark.sql.columnar._
 import org.apache.spark.sql.columnar.ColumnarTestUtils._
+import org.apache.spark.sql.types.NativeType
 
 class DictionaryEncodingSuite extends FunSuite {
   testDictionaryEncoding(new IntColumnStats,    INT)

sql/core/src/test/scala/org/apache/spark/sql/columnar/compression/IntegralDeltaSuite.scala

@@ -20,9 +20,9 @@ package org.apache.spark.sql.columnar.compression
 import org.scalatest.FunSuite
 
 import org.apache.spark.sql.catalyst.expressions.GenericMutableRow
-import org.apache.spark.sql.types.IntegralType
 import org.apache.spark.sql.columnar._
 import org.apache.spark.sql.columnar.ColumnarTestUtils._
+import org.apache.spark.sql.types.IntegralType
 
 class IntegralDeltaSuite extends FunSuite {
   testIntegralDelta(new IntColumnStats,  INT,  IntDelta)

sql/core/src/test/scala/org/apache/spark/sql/columnar/compression/RunLengthEncodingSuite.scala

@@ -20,9 +20,9 @@ package org.apache.spark.sql.columnar.compression
 import org.scalatest.FunSuite
 
 import org.apache.spark.sql.catalyst.expressions.GenericMutableRow
-import org.apache.spark.sql.types.NativeType
 import org.apache.spark.sql.columnar._
 import org.apache.spark.sql.columnar.ColumnarTestUtils._
+import org.apache.spark.sql.types.NativeType
 
 class RunLengthEncodingSuite extends FunSuite {
   testRunLengthEncoding(new NoopColumnStats, BOOLEAN)

sql/core/src/test/scala/org/apache/spark/sql/columnar/compression/TestCompressibleColumnBuilder.scala

@@ -17,8 +17,8 @@
 
 package org.apache.spark.sql.columnar.compression
 
-import org.apache.spark.sql.types.NativeType
 import org.apache.spark.sql.columnar._
+import org.apache.spark.sql.types.NativeType
 
 class TestCompressibleColumnBuilder[T <: NativeType](
     override val columnStats: ColumnStats,

sql/core/src/test/scala/org/apache/spark/sql/json/JsonSuite.scala

@@ -17,19 +17,19 @@
 
 package org.apache.spark.sql.json
 
-import org.apache.spark.sql.types._
-import org.apache.spark.sql.types.decimal.Decimal
-import org.apache.spark.sql.catalyst.util._
-import org.apache.spark.sql.json.JsonRDD.{enforceCorrectType, compatibleType}
-import org.apache.spark.sql.{Row, SQLConf, QueryTest}
+import java.sql.{Date, Timestamp}
+
 import org.apache.spark.sql.TestData._
+import org.apache.spark.sql.catalyst.util._
+import org.apache.spark.sql.json.JsonRDD.{compatibleType, enforceCorrectType}
 import org.apache.spark.sql.test.TestSQLContext
 import org.apache.spark.sql.test.TestSQLContext._
-
-import java.sql.{Date, Timestamp}
+import org.apache.spark.sql.types._
+import org.apache.spark.sql.types.decimal.Decimal
+import org.apache.spark.sql.{QueryTest, Row, SQLConf}
 
 class JsonSuite extends QueryTest {
-  import TestJsonData._
+  import org.apache.spark.sql.json.TestJsonData._
   TestJsonData
 
   test("Type promotion") {