gengliangwang 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_r294153497
########## File path: sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/SchemaMergeUtils.scala ########## @@ -0,0 +1,105 @@ +/* + * 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 + +import org.apache.hadoop.conf.Configuration +import org.apache.hadoop.fs.{FileStatus, Path} + +import org.apache.spark.SparkException +import org.apache.spark.internal.Logging +import org.apache.spark.sql.SparkSession +import org.apache.spark.sql.types.StructType +import org.apache.spark.util.SerializableConfiguration + +object SchemaMergeUtils extends Logging { + /** + * Figures out a merged Parquet/ORC schema with a distributed Spark job. + */ + def mergeSchemasInParallel( + sparkSession: SparkSession, + files: Seq[FileStatus], + schemaReader: (Seq[FileStatus], Configuration, Boolean) => Seq[StructType]) + : Option[StructType] = { + val serializedConf = new SerializableConfiguration(sparkSession.sessionState.newHadoopConf()) + + // !! HACK ALERT !! + // + // Parquet/ORC requires `FileStatus`es to read footers. Review comment: Sorry, I check the code again and I think only Parquet requires `FileStatus`, while Orc requires only `Path`. So the comments here are not accurate. We should explain that the hack is for Parquet, but it can be used by ORC as well. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
