Github user dongjoon-hyun commented on a diff in the pull request: https://github.com/apache/spark/pull/19651#discussion_r150301486 --- Diff: sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/orc/OrcUtils.scala --- @@ -0,0 +1,131 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.spark.sql.execution.datasources.orc + +import java.io.IOException + +import scala.collection.JavaConverters._ + +import org.apache.hadoop.conf.Configuration +import org.apache.hadoop.fs.{FileStatus, Path} +import org.apache.orc.{OrcFile, TypeDescription} + +import org.apache.spark.deploy.SparkHadoopUtil +import org.apache.spark.internal.Logging +import org.apache.spark.sql.SparkSession +import org.apache.spark.sql.catalyst.analysis.Resolver +import org.apache.spark.sql.catalyst.parser.CatalystSqlParser +import org.apache.spark.sql.types._ + +object OrcUtils extends Logging { + + // The extensions for ORC compression codecs + val extensionsForCompressionCodecNames = Map( + "NONE" -> "", + "SNAPPY" -> ".snappy", + "ZLIB" -> ".zlib", + "LZO" -> ".lzo") + + def listOrcFiles(pathStr: String, conf: Configuration): Seq[Path] = { + val origPath = new Path(pathStr) + val fs = origPath.getFileSystem(conf) + val paths = SparkHadoopUtil.get.listLeafStatuses(fs, origPath) + .filterNot(_.isDirectory) + .map(_.getPath) + .filterNot(_.getName.startsWith("_")) + .filterNot(_.getName.startsWith(".")) + paths + } + + private[orc] def readSchema(file: Path, conf: Configuration): Option[TypeDescription] = { + try { + val fs = file.getFileSystem(conf) + val readerOptions = OrcFile.readerOptions(conf).filesystem(fs) + val reader = OrcFile.createReader(file, readerOptions) + val schema = reader.getSchema + if (schema.getFieldNames.size == 0) { + None + } else { + Some(schema) + } + } catch { + case _: IOException => None + } + } + + private[orc] def readSchema(sparkSession: SparkSession, files: Seq[FileStatus]) + : Option[StructType] = { + val conf = sparkSession.sessionState.newHadoopConf() + files.map(_.getPath).flatMap(readSchema(_, conf)).headOption.map { schema => + logDebug(s"Reading schema from file $files, got Hive schema string: $schema") + CatalystSqlParser.parseDataType(schema.toString).asInstanceOf[StructType] + } + } + + private[orc] def getSchemaString(schema: StructType): String = { + schema.fields.map(f => s"${f.name}:${f.dataType.catalogString}").mkString("struct<", ",", ">") + } + + private[orc] def getTypeDescription(dataType: DataType) = dataType match { + case st: StructType => TypeDescription.fromString(getSchemaString(st)) + case _ => TypeDescription.fromString(dataType.catalogString) + } + + /** + * Return a missing schema in a give ORC file. + */ + private[orc] def getMissingSchema( --- End diff -- Correct. So far, it does.
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