[GitHub] HuangZhenQiu commented on a change in pull request #6483: [Flink-7243][flink-formats] Add parquet input format

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HuangZhenQiu commented on a change in pull request #6483: [Flink-7243][flink-formats] Add parquet input format
URL: https://github.com/apache/flink/pull/6483#discussion_r211128582
 
 

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 File path: flink-formats/flink-parquet/src/main/java/org/apache/flink/formats/parquet/ParquetInputFormat.java
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+/*
+ * 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.flink.formats.parquet;
+
+import org.apache.flink.api.common.io.CheckpointableInputFormat;
+import org.apache.flink.api.common.io.FileInputFormat;
+import org.apache.flink.api.common.typeinfo.TypeInformation;
+import org.apache.flink.api.java.tuple.Tuple2;
+import org.apache.flink.api.java.typeutils.RowTypeInfo;
+import org.apache.flink.core.fs.FileInputSplit;
+import org.apache.flink.core.fs.Path;
+import org.apache.flink.formats.parquet.utils.ParquetRecordReader;
+import org.apache.flink.formats.parquet.utils.ParquetSchemaConverter;
+import org.apache.flink.formats.parquet.utils.RowReadSupport;
+import org.apache.flink.metrics.Counter;
+import org.apache.flink.types.Row;
+import org.apache.flink.util.Preconditions;
+
+import org.apache.parquet.ParquetReadOptions;
+import org.apache.parquet.hadoop.ParquetFileReader;
+import org.apache.parquet.hadoop.util.HadoopInputFile;
+import org.apache.parquet.io.InputFile;
+import org.apache.parquet.schema.MessageType;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.IOException;
+
+/**
+ * The base InputFormat class to read from Parquet files.
+ * For specific return types the {@link #convert(Row)} method need to be implemented.
+ *
+ * <P>Using {@link ParquetRecordReader} to Read files instead of {@link org.apache.flink.core.fs.FSDataInputStream},
+ * we override {@link #open(FileInputSplit)} and {@link #close()} to change the behaviors.
+ *
+ * @param <E> The type of record to read.
+ */
+public abstract class ParquetInputFormat<E> extends FileInputFormat<E> implements
+	CheckpointableInputFormat<FileInputSplit, Tuple2<Long, Long>> {
+
+	private static final long serialVersionUID = 1L;
+
+	private static final Logger LOG = LoggerFactory.getLogger(ParquetInputFormat.class);
+
+	private transient Counter recordConsumed;
+
+	protected RowTypeInfo readType;
+
+	protected final TypeInformation[] fieldTypes;
+
+	protected final String[] fieldNames;
+
+	protected transient ParquetRecordReader<Row> parquetRecordReader;
+
+	protected transient long recordsReadSinceLastSync;
+
+	protected long lastSyncedBlock = -1L;
+
+	protected ParquetInputFormat(
+		Path path, TypeInformation[] fieldTypes, String[] fieldNames) {
+		super(path);
+		this.readType = new RowTypeInfo(fieldTypes, fieldNames);
+		this.fieldTypes = readType.getFieldTypes();
+		this.fieldNames = readType.getFieldNames();
+		this.unsplittable = true;
+	}
+
+	@Override
+	public Tuple2<Long, Long> getCurrentState() {
+		return new Tuple2<>(this.lastSyncedBlock, this.recordsReadSinceLastSync);
+	}
+
+	@Override
+	public void open(FileInputSplit split) throws IOException {
+		org.apache.hadoop.conf.Configuration configuration = new org.apache.hadoop.conf.Configuration();
+		InputFile inputFile =
+			HadoopInputFile.fromPath(new org.apache.hadoop.fs.Path(split.getPath().toUri()), configuration);
+		ParquetReadOptions options = ParquetReadOptions.builder().build();
+		ParquetFileReader fileReader = new ParquetFileReader(inputFile, options);
+		MessageType schema = fileReader.getFileMetaData().getSchema();
+		checkSchema(schema);
+		MessageType readSchema = ParquetSchemaConverter.toParquetType(readType);
 
 Review comment:
   The checkSchema function needs to read the parquet footer first. It is too heavy to open and read through all of the files in constructor. 

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