Github user dongjoon-hyun commented on a diff in the pull request:
https://github.com/apache/spark/pull/19651#discussion_r150431325
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/orc/OrcUtils.scala
---
@@ -0,0 +1,138 @@
+/*
+ * 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 scala.collection.mutable.ArrayBuffer
+
+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.{caseInsensitiveResolution,
caseSensitiveResolution}
+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 withNullSafe(f: Any => Any): Any => Any = {
+ input => if (input == null) null else f(input)
+ }
+
+ 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()
+ // TODO: We need to support merge schema. Please see SPARK-11412.
+ 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}:${f.dataType.catalogString}").mkString("struct<", ",", ">")
+ }
+
+ private[orc] def getTypeDescription(dataType: DataType) = dataType match
{
+ case st: StructType => TypeDescription.fromString(getSchemaString(st))
+ case _ => TypeDescription.fromString(dataType.catalogString)
+ }
+
+ /**
+ * Return missing column names in a give ORC file.
+ */
+ private[orc] def getMissingColumnNames(
+ isCaseSensitive: Boolean,
+ dataSchema: StructType,
+ partitionSchema: StructType,
+ file: Path,
+ conf: Configuration): Option[Seq[String]] = {
+ val resolver = if (isCaseSensitive) caseSensitiveResolution else
caseInsensitiveResolution
+ try {
+ val fs = file.getFileSystem(conf)
+ val readerOptions = OrcFile.readerOptions(conf).filesystem(fs)
+ val reader = OrcFile.createReader(file, readerOptions)
+ val schema = reader.getSchema
+ if (schema.getFieldNames.size == 0) {
+ None
+ } else {
+ val orcSchema = if
(schema.getFieldNames.asScala.forall(_.startsWith("_col"))) {
+ logInfo("Recover ORC schema with data schema")
+ var schemaString = schema.toString
+ dataSchema.zipWithIndex.foreach { case (field: StructField,
index: Int) =>
+ schemaString = schemaString.replace(s"_col$index:",
s"${field.name}:")
+ }
+ TypeDescription.fromString(schemaString)
+ } else {
+ schema
+ }
+
+ val missingColumnNames = new ArrayBuffer[String]
+ if (dataSchema.length > orcSchema.getFieldNames.size) {
+ dataSchema.filter(x =>
partitionSchema.getFieldIndex(x.name).isEmpty).foreach { f =>
+ if (!orcSchema.getFieldNames.asScala.exists(resolver(_,
f.name))) {
+ missingColumnNames += f.name
+ }
+ }
+ }
+ Some(missingColumnNames)
+ }
+ } catch {
+ case _: IOException => None
--- End diff --
For this, let me think this for a while.
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