shangxinli commented on code in PR #14435: URL: https://github.com/apache/iceberg/pull/14435#discussion_r2583609585
########## spark/v4.0/spark/src/main/java/org/apache/iceberg/spark/actions/SparkParquetFileMergeRunner.java: ########## @@ -0,0 +1,504 @@ +/* + * 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.spark.actions; + +import java.io.IOException; +import java.io.Serializable; +import java.nio.ByteBuffer; +import java.util.List; +import java.util.Map; +import java.util.Set; +import java.util.stream.Collectors; +import org.apache.hadoop.conf.Configuration; +import org.apache.iceberg.DataFile; +import org.apache.iceberg.DataFiles; +import org.apache.iceberg.FileFormat; +import org.apache.iceberg.MetadataColumns; +import org.apache.iceberg.Metrics; +import org.apache.iceberg.MetricsConfig; +import org.apache.iceberg.PartitionSpec; +import org.apache.iceberg.StructLike; +import org.apache.iceberg.Table; +import org.apache.iceberg.TableProperties; +import org.apache.iceberg.TableUtil; +import org.apache.iceberg.actions.RewriteFileGroup; +import org.apache.iceberg.encryption.EncryptedOutputFile; +import org.apache.iceberg.io.FileIO; +import org.apache.iceberg.io.InputFile; +import org.apache.iceberg.io.OutputFileFactory; +import org.apache.iceberg.parquet.ParquetFileMerger; +import org.apache.iceberg.parquet.ParquetUtil; +import org.apache.iceberg.relocated.com.google.common.annotations.VisibleForTesting; +import org.apache.iceberg.relocated.com.google.common.collect.Lists; +import org.apache.iceberg.relocated.com.google.common.collect.Sets; +import org.apache.iceberg.spark.FileRewriteCoordinator; +import org.apache.iceberg.types.Conversions; +import org.apache.iceberg.types.Types; +import org.apache.iceberg.util.PropertyUtil; +import org.apache.parquet.schema.MessageType; +import org.apache.spark.api.java.JavaRDD; +import org.apache.spark.api.java.JavaSparkContext; +import org.apache.spark.sql.SparkSession; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * Extension of SparkBinPackFileRewriteRunner that uses ParquetFileMerger for efficient row-group + * level merging of Parquet files when applicable. + * + * <p>This runner uses {@link ParquetFileMerger} to merge Parquet files at the row-group level + * without full deserialization, which is significantly faster than the standard Spark rewrite + * approach for Parquet files. + * + * <p>The decision to use this runner vs. SparkBinPackFileRewriteRunner is controlled by the + * configuration option {@code use-parquet-file-merger}. + */ +public class SparkParquetFileMergeRunner extends SparkBinPackFileRewriteRunner { + private static final Logger LOG = LoggerFactory.getLogger(SparkParquetFileMergeRunner.class); + private final FileRewriteCoordinator coordinator = FileRewriteCoordinator.get(); + + public SparkParquetFileMergeRunner(SparkSession spark, Table table) { + super(spark, table); + } + + @Override + public String description() { + return "PARQUET-MERGE"; + } + + @Override + protected void doRewrite(String groupId, RewriteFileGroup group) { + // Early validation: check if requirements are met + if (!canMerge(group)) { + LOG.info( + "Row-group merge requirements not met for group {}. Using standard Spark rewrite.", + groupId); + super.doRewrite(groupId, group); + return; + } + + // Requirements met - attempt row-group level merge + try { + LOG.info( + "Merging {} Parquet files using row-group level merge (group: {})", + group.rewrittenFiles().size(), + groupId); + mergeParquetFilesDistributed(groupId, group); + } catch (Exception e) { + LOG.info( + "Row-group merge failed for group {}, falling back to standard Spark rewrite: {}", + groupId, + e.getMessage(), + e); + // Fallback to standard rewrite + super.doRewrite(groupId, group); + } + } + + /** + * Validates if the file group can use row-group level merging. + * + * <p>Requirements checked here: + * + * <ul> + * <li>Table must not have a sort order (no sorting or z-ordering) + * <li>Files must not have delete files or delete vectors + * <li>Partition spec must not be changing (row-group merge cannot repartition data) + * <li>Must not be splitting large files (row-group merge is optimized for merging, not + * splitting) + * </ul> + * + * <p>Additional requirements checked by ParquetFileMerger.canMerge: + * + * <ul> + * <li>All files must be valid Parquet format + * <li>Files must have compatible schemas + * <li>Files must not be encrypted + * <li>If a physical _row_id column exists, all values must be non-null + * </ul> + * + * @param group the file group to check + * @return true if row-group merging can be used, false otherwise + */ + @VisibleForTesting + boolean canMerge(RewriteFileGroup group) { + // Check if table has a sort order - row-group merge cannot preserve sort order + if (table().sortOrder().isSorted()) { + LOG.debug( + "Cannot use row-group merge: table has a sort order ({}). " + + "Row-group merging would not preserve the sort order.", + table().sortOrder()); + return false; + } + + // Check for delete files - row-group merge cannot apply deletes + boolean hasDeletes = group.fileScanTasks().stream().anyMatch(task -> !task.deletes().isEmpty()); + + if (hasDeletes) { + LOG.debug( + "Cannot use row-group merge: files have delete files or delete vectors. " + + "Row-group merging cannot apply deletes."); + return false; + } + + // Check if partition spec is being changed - row-group merge cannot repartition data + int outputSpecId = group.outputSpecId(); + boolean hasPartitionSpecChange = + group.rewrittenFiles().stream().anyMatch(file -> file.specId() != outputSpecId); + + if (hasPartitionSpecChange) { + LOG.debug( + "Cannot use row-group merge: partition spec is changing. " + + "Row-group merging cannot change data partitioning."); + return false; + } + + // Check if we're splitting large files - row-group merge is designed for file merging, not + // splitting + long maxOutputFileSize = group.maxOutputFileSize(); + boolean isSplittingFiles = + group.rewrittenFiles().stream() + .anyMatch(file -> file.fileSizeInBytes() > maxOutputFileSize); + + if (isSplittingFiles) { + LOG.debug( + "Cannot use row-group merge: compaction is splitting large files. " + + "Row-group merging is optimized for merging files, not splitting them."); + return false; + } + + // Validate schema compatibility and other Parquet-specific requirements + try { + List<InputFile> inputFiles = + group.rewrittenFiles().stream() + .map(f -> table().io().newInputFile(f.path().toString())) + .collect(Collectors.toList()); + + // Validate files can be merged + boolean canMerge = ParquetFileMerger.canMerge(inputFiles); + + if (!canMerge) { + LOG.info( + "Cannot use row-group merge for {} files. Falling back to standard rewrite. " + + "Reason: Parquet validation failed", + group.rewrittenFiles().size()); + } + + return canMerge; + } catch (Exception e) { + LOG.info("Cannot use row-group merge: validation failed", e); + return false; + } + } + + /** + * Merges Parquet files in the group, respecting the expected output file count determined by the + * planner. Files are distributed evenly across the expected number of output files. + */ + private void mergeParquetFilesDistributed(String groupId, RewriteFileGroup group) { + PartitionSpec spec = table().specs().get(group.outputSpecId()); + StructLike partition = group.info().partition(); + int expectedOutputFiles = group.expectedOutputFiles(); + + LOG.info( + "Merging {} Parquet files into {} expected output files (group: {})", + group.rewrittenFiles().size(), + expectedOutputFiles, + groupId); + + // Check if table supports row lineage + boolean preserveRowLineage = TableUtil.supportsRowLineage(table()); + + // Distribute files evenly across expected output files (planner already determined the count) + List<List<DataFile>> fileBatches = + distributeFilesEvenly(group.rewrittenFiles(), expectedOutputFiles); Review Comment: - Added validation in canMerge() to require expectedOutputFiles == 1 - Groups with multiple expected files gracefully fall back to standard bin-pack rewrite - Removed distributeFilesEvenly() bin-packing method (45 lines) - Simplified batching logic: removed loops for creating tasks and processing results -- This is an automated message from the Apache Git Service. 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