[SPARK-16162] Remove dead code OrcTableScan.

## What changes were proposed in this pull request?

SPARK-14535 removed all calls to class OrcTableScan. This removes the dead code.

## How was this patch tested?

Existing unit tests.

Author: Brian Cho <bcho@fb.com>

Closes #13869 from dafrista/clean-up-orctablescan.

sql/hive/src/main/scala/org/apache/spark/sql/hive/orc/OrcFileFormat.scala

@@ -27,12 +27,10 @@ import org.apache.hadoop.hive.ql.io.orc._
 import org.apache.hadoop.hive.serde2.objectinspector.{SettableStructObjectInspector, StructObjectInspector}
 import org.apache.hadoop.hive.serde2.typeinfo.{StructTypeInfo, TypeInfoUtils}
 import org.apache.hadoop.io.{NullWritable, Writable}
-import org.apache.hadoop.mapred.{InputFormat => MapRedInputFormat, JobConf, OutputFormat => MapRedOutputFormat, RecordWriter, Reporter}
+import org.apache.hadoop.mapred.{JobConf, OutputFormat => MapRedOutputFormat, RecordWriter, Reporter}
 import org.apache.hadoop.mapreduce._
 import org.apache.hadoop.mapreduce.lib.input.{FileInputFormat, FileSplit}
 
-import org.apache.spark.internal.Logging
-import org.apache.spark.rdd.{HadoopRDD, RDD}
 import org.apache.spark.sql.{Row, SparkSession}
 import org.apache.spark.sql.catalyst.InternalRow
 import org.apache.spark.sql.catalyst.expressions._
@@ -260,69 +258,6 @@ private[orc] class OrcOutputWriter(
   }
 }
 
-private[orc] case class OrcTableScan(
-    @transient sparkSession: SparkSession,
-    attributes: Seq[Attribute],
-    filters: Array[Filter],
-    @transient inputPaths: Seq[FileStatus])
-  extends Logging
-  with HiveInspectors {
-
-  def execute(): RDD[InternalRow] = {
-    val job = Job.getInstance(sparkSession.sessionState.newHadoopConf())
-    val conf = job.getConfiguration
-
-    // Figure out the actual schema from the ORC source (without partition columns) so that we
-    // can pick the correct ordinals.  Note that this assumes that all files have the same schema.
-    val orcFormat = new OrcFileFormat
-    val dataSchema =
-      orcFormat
-        .inferSchema(sparkSession, Map.empty, inputPaths)
-        .getOrElse(sys.error("Failed to read schema from target ORC files."))
-
-    // Tries to push down filters if ORC filter push-down is enabled
-    if (sparkSession.sessionState.conf.orcFilterPushDown) {
-      OrcFilters.createFilter(dataSchema, filters).foreach { f =>
-        conf.set(OrcTableScan.SARG_PUSHDOWN, f.toKryo)
-        conf.setBoolean(ConfVars.HIVEOPTINDEXFILTER.varname, true)
-      }
-    }
-
-    // Sets requested columns
-    OrcRelation.setRequiredColumns(conf, dataSchema, StructType.fromAttributes(attributes))
-
-    if (inputPaths.isEmpty) {
-      // the input path probably be pruned, return an empty RDD.
-      return sparkSession.sparkContext.emptyRDD[InternalRow]
-    }
-    FileInputFormat.setInputPaths(job, inputPaths.map(_.getPath): _*)
-
-    val inputFormatClass =
-      classOf[OrcInputFormat]
-        .asInstanceOf[Class[_ <: MapRedInputFormat[NullWritable, Writable]]]
-
-    val rdd = sparkSession.sparkContext.hadoopRDD(
-      conf.asInstanceOf[JobConf],
-      inputFormatClass,
-      classOf[NullWritable],
-      classOf[Writable]
-    ).asInstanceOf[HadoopRDD[NullWritable, Writable]]
-
-    val wrappedConf = new SerializableConfiguration(conf)
-
-    rdd.mapPartitionsWithInputSplit { case (split: OrcSplit, iterator) =>
-      val writableIterator = iterator.map(_._2)
-      val maybeStructOI = OrcFileOperator.getObjectInspector(split.getPath.toString, Some(conf))
-      OrcRelation.unwrapOrcStructs(
-        wrappedConf.value,
-        StructType.fromAttributes(attributes),
-        maybeStructOI,
-        writableIterator
-      )
-    }
-  }
-}
-
 private[orc] object OrcTableScan {
   // This constant duplicates `OrcInputFormat.SARG_PUSHDOWN`, which is unfortunately not public.
   private[orc] val SARG_PUSHDOWN = "sarg.pushdown"