shangxinli commented on code in PR #14435: URL: https://github.com/apache/iceberg/pull/14435#discussion_r2583656473
########## parquet/src/main/java/org/apache/iceberg/parquet/ParquetFileMerger.java: ########## @@ -0,0 +1,643 @@ +/* + * 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.Locale; +import java.util.Map; +import java.util.function.LongUnaryOperator; +import org.apache.hadoop.conf.Configuration; +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.DirectByteBufferAllocator; +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.statistics.Statistics; +import org.apache.parquet.column.values.ValuesWriter; +import org.apache.parquet.column.values.delta.DeltaBinaryPackingValuesWriterForLong; +import org.apache.parquet.crypto.InternalFileEncryptor; +import org.apache.parquet.hadoop.CodecFactory; +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> + * ValidationResult result = ParquetFileMerger.readAndValidateSchema(inputFiles); + * if (result != null) { + * ParquetFileMerger.mergeFiles( + * inputFiles, encryptedOutputFile, result.schema(), firstRowIds, + * rowGroupSize, columnIndexTruncateLength, result.metadata()); + * } + * </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 + } + + /** + * Validates that all input files can be merged. + * + * <p>This method validates that: + * + * <ul> + * <li>All files are valid Parquet format (detected by reading Parquet footer) + * <li>All files have identical schemas + * <li>Files are not encrypted (detected by ParquetCryptoRuntimeException) + * <li>If physical row lineage columns exist, all values are non-null + * </ul> + * + * <p>This method works with any Iceberg FileIO implementation (S3FileIO, GCSFileIO, etc.). + * + * @param inputFiles List of Iceberg input files to validate + * @return true if files can be merged, false otherwise + */ + public static boolean canMerge(List<InputFile> inputFiles) { + try { + if (inputFiles == null || inputFiles.isEmpty()) { + return false; + } + + // Read schema from the first file + MessageType firstSchema = readSchema(inputFiles.get(0)); + + // Check if schema has physical row lineage columns + boolean hasRowIdColumn = firstSchema.containsField(MetadataColumns.ROW_ID.name()); + boolean hasSeqNumColumn = + firstSchema.containsField(MetadataColumns.LAST_UPDATED_SEQUENCE_NUMBER.name()); + + // Validate all files have the same schema + for (int i = 1; i < inputFiles.size(); i++) { + MessageType currentSchema = readSchema(inputFiles.get(i)); + + if (!firstSchema.equals(currentSchema)) { + return false; + } + } + + // If there are physical row lineage columns, validate no nulls + if (hasRowIdColumn || hasSeqNumColumn) { + validateRowLineageColumnsHaveNoNulls(inputFiles); + } + + return true; + } catch (RuntimeException | IOException e) { + // Returns false for: + // - Non-Parquet files (IOException when reading Parquet footer) + // - Encrypted files (ParquetCryptoRuntimeException extends RuntimeException) + // - Files with null row lineage values (IllegalArgumentException from + // validateRowLineageColumnsHaveNoNulls) + // - Any other validation failures + return false; + } + } + + /** + * 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 + */ + public static MessageType readSchema(InputFile inputFile) throws IOException { Review Comment: Made them private -- This is an automated message from the Apache Git Service. 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