WangGuangxin commented on a change in pull request #3852: add support for parquet reader URL: https://github.com/apache/incubator-pinot/pull/3852#discussion_r260191940
########## File path: pinot-common/src/main/java/org/apache/pinot/common/utils/ParquetUtils.java ########## @@ -0,0 +1,100 @@ +/** + * 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.pinot.common.utils; + +import org.apache.avro.Schema; +import org.apache.avro.generic.GenericData; +import org.apache.avro.generic.GenericRecord; +import org.apache.hadoop.conf.Configuration; +import org.apache.hadoop.fs.Path; +import org.apache.parquet.avro.AvroParquetReader; +import org.apache.parquet.avro.AvroParquetWriter; +import org.apache.parquet.avro.AvroSchemaConverter; +import org.apache.parquet.hadoop.ParquetFileReader; +import org.apache.parquet.hadoop.ParquetReader; +import org.apache.parquet.hadoop.ParquetWriter; +import org.apache.parquet.hadoop.metadata.ParquetMetadata; + +import java.io.IOException; +import java.util.List; + + +public class ParquetUtils { + /** + * Get a ParquetReader with the given file. + * @param fileName the parquet file to read + * @return a ParquetReader + * @throws IOException + */ + public static ParquetReader<GenericRecord> getParquetReader(String fileName) + throws IOException { + Path dataFsPath = new Path(fileName); + return AvroParquetReader.<GenericRecord>builder(dataFsPath).disableCompatibility().withDataModel(GenericData.get()) + .withConf(getConfiguration()).build(); + } + + /** + * Read the parquet file schema + * @param fileName + * @return the parquet file schema + * @throws IOException + */ + public static Schema getParquetSchema(String fileName) + throws IOException { + Path dataFsPath = new Path(fileName); + ParquetMetadata footer = ParquetFileReader.readFooter(getConfiguration(), dataFsPath); + + String schemaString = footer.getFileMetaData().getKeyValueMetaData().get("parquet.avro.schema"); + if (schemaString == null) { + // try the older property + schemaString = footer.getFileMetaData().getKeyValueMetaData().get("avro.schema"); + } + + if (schemaString != null) { + return new Schema.Parser().parse(schemaString); + } else { + return new AvroSchemaConverter().convert(footer.getFileMetaData().getSchema()); + } + } + + /** + * write records as parquet file + */ + public static void writeParquetRecord(String fileName, Schema schema, List<GenericRecord> records) + throws IOException { + ParquetWriter<GenericRecord> writer = + AvroParquetWriter.<GenericRecord>builder(new Path(fileName)).withSchema(schema).withConf(getConfiguration()) + .build(); + + try { + for (GenericRecord r : records) { + writer.write(r); + } + } finally { + writer.close(); + } + } + + private static Configuration getConfiguration() { Review comment: > Will `fs.defaultFS` and `fs.file.impl` automatically get overridden when we run this on Hadoop? yes, it will automatically get overridden. But sometimes, users may change `fs.defaultFS` in their hadoop conf to `hdfs://`. In that case, this job will fail because the file path passed to `*RecordReader` is a local file. So we have to either add `file://` prefix to file path to denote that this is a local file, or make sure `fs.defaultFS` is `file://`. How about add a comment to `getConfiguration` ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on 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]
