shangxinli commented on code in PR #14435: URL: https://github.com/apache/iceberg/pull/14435#discussion_r2562988328
########## parquet/src/main/java/org/apache/iceberg/parquet/ParquetFileMerger.java: ########## @@ -0,0 +1,421 @@ +/* + * 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.iceberg.parquet; + +import static java.util.Collections.emptyMap; + +import java.io.IOException; +import java.util.List; +import java.util.Map; +import org.apache.iceberg.MetadataColumns; +import org.apache.iceberg.encryption.EncryptedOutputFile; +import org.apache.iceberg.io.InputFile; +import org.apache.iceberg.io.OutputFile; +import org.apache.iceberg.io.SeekableInputStream; +import org.apache.iceberg.relocated.com.google.common.collect.Lists; +import org.apache.parquet.bytes.BytesInput; +import org.apache.parquet.bytes.HeapByteBufferAllocator; +import org.apache.parquet.column.ColumnDescriptor; +import org.apache.parquet.column.Encoding; +import org.apache.parquet.column.ParquetProperties; +import org.apache.parquet.column.statistics.LongStatistics; +import org.apache.parquet.column.values.ValuesWriter; +import org.apache.parquet.column.values.delta.DeltaBinaryPackingValuesWriterForLong; +import org.apache.parquet.hadoop.ParquetFileReader; +import org.apache.parquet.hadoop.ParquetFileWriter; +import org.apache.parquet.hadoop.metadata.BlockMetaData; +import org.apache.parquet.hadoop.metadata.ColumnChunkMetaData; +import org.apache.parquet.hadoop.metadata.CompressionCodecName; +import org.apache.parquet.io.DelegatingSeekableInputStream; +import org.apache.parquet.schema.MessageType; +import org.apache.parquet.schema.PrimitiveType; +import org.apache.parquet.schema.Type; +import org.apache.parquet.schema.Types; + +/** + * Utility class for performing strict schema validation and merging of Parquet files at the + * row-group level. + * + * <p>This class ensures that all input files have identical Parquet schemas before merging. The + * merge operation is performed by copying row groups directly without + * serialization/deserialization, providing significant performance benefits over traditional + * read-rewrite approaches. + * + * <p>This class works with any Iceberg FileIO implementation (HadoopFileIO, S3FileIO, GCSFileIO, + * etc.), making it cloud-agnostic. + * + * <p>TODO: Encrypted tables are not supported + * + * <p>Key features: + * + * <ul> + * <li>Row group merging without deserialization using {@link ParquetFileWriter#appendFile} + * <li>Strict schema validation - all files must have identical {@link MessageType} + * <li>Metadata merging for Iceberg-specific footer data + * <li>Works with any FileIO implementation (local, S3, GCS, Azure, etc.) + * </ul> + * + * <p>Restrictions: + * + * <ul> + * <li>All files must have compatible schemas (identical {@link MessageType}) + * <li>Files must not be encrypted + * <li>Files must not have associated delete files or delete vectors + * <li>Table must not have a sort order (including z-ordered tables) + * </ul> + * + * <p>Typical usage: + * + * <pre> + * FileIO fileIO = table.io(); + * List<InputFile> inputFiles = Arrays.asList( + * fileIO.newInputFile("s3://bucket/file1.parquet"), + * fileIO.newInputFile("s3://bucket/file2.parquet") + * ); + * OutputFile outputFile = fileIO.newOutputFile("s3://bucket/merged.parquet"); + * long rowGroupSize = 128 * 1024 * 1024; // 128 MB + * int columnIndexTruncateLength = 64; // Default truncation length + * ParquetFileMerger.mergeFiles(inputFiles, outputFile, rowGroupSize, columnIndexTruncateLength, null); + * </pre> + */ +public class ParquetFileMerger { + // Default buffer sizes for DeltaBinaryPackingValuesWriter + private static final int DEFAULT_INITIAL_BUFFER_SIZE = 64 * 1024; // 64KB + private static final int DEFAULT_PAGE_SIZE_FOR_ENCODING = 64 * 1024; // 64KB + + private ParquetFileMerger() { + // Utility class - prevent instantiation + } + + /** + * Reads and validates that all input files have identical Parquet schemas. + * + * <p>This method works with any Iceberg FileIO implementation (S3FileIO, GCSFileIO, etc.). + * + * @param inputFiles List of Iceberg input files to validate + * @return the common Parquet schema if all files have identical schemas, null otherwise + */ + public static MessageType readAndValidateSchema(List<InputFile> inputFiles) { + try { + if (inputFiles == null || inputFiles.isEmpty()) { + return null; + } + + // Read schema from the first file + MessageType firstSchema = readSchema(inputFiles.get(0)); + + // Validate all remaining files have the same schema + for (int i = 1; i < inputFiles.size(); i++) { + MessageType currentSchema = readSchema(inputFiles.get(i)); + + if (!firstSchema.equals(currentSchema)) { + return null; + } + } + + return firstSchema; + } catch (IllegalArgumentException | IOException e) { + return null; + } + } + + /** + * Reads the Parquet schema from an Iceberg InputFile. + * + * @param inputFile Iceberg input file to read schema from + * @return MessageType schema of the Parquet file + * @throws IOException if reading fails + */ + private static MessageType readSchema(InputFile inputFile) throws IOException { + return ParquetFileReader.open(ParquetIO.file(inputFile)) + .getFooter() + .getFileMetaData() + .getSchema(); + } + + /** Internal method to merge files when schema is already known. */ + private static void mergeFilesWithSchema( + List<InputFile> inputFiles, + OutputFile outputFile, + MessageType schema, + long rowGroupSize, + int columnIndexTruncateLength, + Map<String, String> extraMetadata) + throws IOException { + try (ParquetFileWriter writer = + new ParquetFileWriter( + ParquetIO.file(outputFile), + schema, + ParquetFileWriter.Mode.CREATE, + rowGroupSize, + 0, // maxPaddingSize - hardcoded to 0 (same as ParquetWriter) + columnIndexTruncateLength, + ParquetProperties.DEFAULT_STATISTICS_TRUNCATE_LENGTH, + ParquetProperties.DEFAULT_PAGE_WRITE_CHECKSUM_ENABLED)) { + + writer.start(); + for (InputFile inputFile : inputFiles) { + writer.appendFile(ParquetIO.file(inputFile)); + } + + if (extraMetadata != null && !extraMetadata.isEmpty()) { + writer.end(extraMetadata); + } else { + writer.end(emptyMap()); + } + } + } + + /** Internal method to merge files with row IDs when base schema is already known. */ + private static void mergeFilesWithRowIdsAndSchema( + List<InputFile> inputFiles, + OutputFile outputFile, + List<Long> firstRowIds, + MessageType baseSchema, Review Comment: Refactored -- This is an automated message from the Apache Git Service. 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