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_r225603693
########## File path: flink-formats/flink-parquet/src/main/java/org/apache/flink/formats/parquet/utils/ParquetRecordReader.java ########## @@ -0,0 +1,196 @@ +/* + * 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.utils; + +import org.apache.hadoop.conf.Configuration; +import org.apache.parquet.column.page.PageReadStore; +import org.apache.parquet.filter2.compat.FilterCompat; +import org.apache.parquet.filter2.compat.FilterCompat.Filter; +import org.apache.parquet.hadoop.ParquetFileReader; +import org.apache.parquet.hadoop.api.InitContext; +import org.apache.parquet.hadoop.api.ReadSupport; +import org.apache.parquet.hadoop.metadata.FileMetaData; +import org.apache.parquet.io.ColumnIOFactory; +import org.apache.parquet.io.MessageColumnIO; +import org.apache.parquet.io.RecordReader; +import org.apache.parquet.io.api.RecordMaterializer; +import org.apache.parquet.io.api.RecordMaterializer.RecordMaterializationException; +import org.apache.parquet.schema.MessageType; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import javax.annotation.CheckReturnValue; +import javax.annotation.meta.When; + +import java.io.IOException; +import java.util.Collections; +import java.util.HashMap; +import java.util.HashSet; +import java.util.Map; +import java.util.Set; + +import static org.apache.parquet.Preconditions.checkNotNull; + +/** + * Customized {@link org.apache.parquet.hadoop.ParquetRecordReader} that support start read from particular position. + */ +public class ParquetRecordReader<T> { + private static final Logger LOG = LoggerFactory.getLogger(ParquetRecordReader.class); + + private ColumnIOFactory columnIOFactory; + private Filter filter; + + private MessageType readSchema; + private MessageType fileSchema; + private ReadSupport<T> readSupport; + + private RecordMaterializer<T> recordMaterializer; + private T currentValue; + private long total; + private long current = 0; + private int currentBlock = -1; + private ParquetFileReader reader; + private RecordReader<T> recordReader; + private boolean strictTypeChecking = true; + private long totalCountLoadedSoFar = 0; + + public ParquetRecordReader(ReadSupport<T> readSupport, MessageType readSchema, Filter filter) { + this.readSupport = readSupport; + this.readSchema = readSchema; + this.filter = checkNotNull(filter, "filter"); + } + + public ParquetRecordReader(ReadSupport<T> readSupport, MessageType readSchema) { + this(readSupport, readSchema, FilterCompat.NOOP); + } + + public void initialize(ParquetFileReader reader, Configuration configuration) { + this.reader = reader; + FileMetaData parquetFileMetadata = reader.getFooter().getFileMetaData(); + this.fileSchema = parquetFileMetadata.getSchema(); + Map<String, String> fileMetadata = parquetFileMetadata.getKeyValueMetaData(); + ReadSupport.ReadContext readContext = readSupport.init(new InitContext( + configuration, toSetMultiMap(fileMetadata), readSchema)); + + this.columnIOFactory = new ColumnIOFactory(parquetFileMetadata.getCreatedBy()); + this.readSchema = readContext.getRequestedSchema(); + this.recordMaterializer = readSupport.prepareForRead( + configuration, fileMetadata, readSchema, readContext); + this.total = reader.getRecordCount(); + reader.setRequestedSchema(readSchema); + } + + private void checkRead() throws IOException { + if (current == totalCountLoadedSoFar) { + PageReadStore pages = reader.readNextRowGroup(); + recordReader = createRecordReader(pages); + totalCountLoadedSoFar += pages.getRowCount(); + currentBlock++; + } + } + + public void close() throws IOException { + if (reader != null) { + reader.close(); + } + } + + @CheckReturnValue(when = When.NEVER) + public T nextRecord() { + return currentValue; + } + + public void seek(long syncedBlock) throws IOException { + PageReadStore pages = null; + while (syncedBlock > 0) { + pages = reader.readNextRowGroup(); + } + + recordReader = createRecordReader(pages); + } + + private RecordReader<T> createRecordReader(PageReadStore pages) throws IOException { + if (pages == null) { + throw new IOException("Expecting more rows but reached last block. Read " + current + " out of " + total); + } + MessageColumnIO columnIO = columnIOFactory.getColumnIO(readSchema, fileSchema, strictTypeChecking); + // TODO (hpeter) enable filter later + RecordReader<T> recordReader = columnIO.getRecordReader(pages, recordMaterializer, FilterCompat.NOOP); + return recordReader; + } + + public long getCurrentBlock() { + return currentBlock; + } + + public boolean reachEnd() { + return current >= total; + } + + public boolean hasNextRecord() throws IOException { + boolean recordFound = false; + + while (!recordFound) { + // no more records left + if (current >= total) { + return false; + } + + try { + checkRead(); + current++; + try { + currentValue = recordReader.read(); + } catch (RecordMaterializationException e) { + LOG.debug("skipping a corrupt record"); + continue; + } + + if (recordReader.shouldSkipCurrentRecord()) { + LOG.debug("skipping record"); + } + + if (currentValue == null) { + current = totalCountLoadedSoFar; + LOG.debug("filtered record reader reached end of block"); + continue; + } + + recordFound = true; + LOG.debug("read value: {}", currentValue); + } catch (RuntimeException e) { + LOG.error(String.format("Can not read value at %d in block %d in file %s", + current, currentBlock, reader.getFile()), e); + return false; Review comment: Agree. 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