[GitHub] [spark] dongjoon-hyun commented on a change in pull request #24043: [SPARK-11412][SQL] Support merge schema for ORC

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dongjoon-hyun commented on a change in pull request #24043: [SPARK-11412][SQL] Support merge schema for ORC
URL: https://github.com/apache/spark/pull/24043#discussion_r281843997
 
 

 ##########
 File path: sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/orc/OrcUtils.scala
 ##########
 @@ -81,14 +82,97 @@ object OrcUtils extends Logging {
       : Option[StructType] = {
     val ignoreCorruptFiles = sparkSession.sessionState.conf.ignoreCorruptFiles
     val conf = sparkSession.sessionState.newHadoopConf()
-    // TODO: We need to support merge schema. Please see SPARK-11412.
     files.toIterator.map(file => readSchema(file.getPath, conf, ignoreCorruptFiles)).collectFirst {
       case Some(schema) =>
         logDebug(s"Reading schema from file $files, got Hive schema string: $schema")
         CatalystSqlParser.parseDataType(schema.toString).asInstanceOf[StructType]
     }
   }
 
+  /**
+   * Read single ORC file schema using native version of ORC
+   */
+  def singleFileSchemaReader(file: String, conf: Configuration, ignoreCorruptFiles: Boolean)
+      : Option[StructType] = {
+    OrcUtils.readSchema(new Path(file), conf, ignoreCorruptFiles)
+      .map(s => CatalystSqlParser.parseDataType(s.toString).asInstanceOf[StructType])
+  }
+
+  /**
+   * Figures out a merged ORC schema with a distributed Spark job.
+   * This function is used by both `org.apache.spark.sql.hive.orc.OrcFileFormat`
+   * and `org.apache.spark.sql.execution.datasources.orc.OrcFileFormat`.
 
 Review comment:
   What happens for `OrcDataSourceV2`?

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