wzhero1 commented on code in PR #7027: URL: https://github.com/apache/paimon/pull/7027#discussion_r2922844126
########## paimon-core/src/main/java/org/apache/paimon/operation/expire/ExpireSnapshotsPlan.java: ########## @@ -0,0 +1,218 @@ +/* + * 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.paimon.operation.expire; + +import java.io.Serializable; +import java.util.ArrayList; +import java.util.Collections; +import java.util.HashMap; +import java.util.List; +import java.util.Map; + +/** + * The plan for snapshot expiration, containing four groups of tasks organized by deletion phase. + * + * <p>The plan organizes tasks into four groups for correct deletion order: + * + * <ul> + * <li>{@link #dataFileTasks()}: Phase 1a - Delete data files (can be parallelized) + * <li>{@link #changelogFileTasks()}: Phase 1b - Delete changelog files (can be parallelized) + * <li>{@link #manifestTasks()}: Phase 2a - Delete manifest files (serial) + * <li>{@link #snapshotFileTasks()}: Phase 2b - Delete snapshot metadata files (serial) + * </ul> + */ +public class ExpireSnapshotsPlan implements Serializable { + + private static final long serialVersionUID = 1L; + + private static final ExpireSnapshotsPlan EMPTY = + new ExpireSnapshotsPlan( + Collections.emptyList(), + Collections.emptyList(), + Collections.emptyList(), + Collections.emptyList(), + null, + 0, + 0); + + private final List<SnapshotExpireTask> dataFileTasks; + private final List<SnapshotExpireTask> changelogFileTasks; + private final List<SnapshotExpireTask> manifestTasks; + private final List<SnapshotExpireTask> snapshotFileTasks; + private final ProtectionSet protectionSet; + private final long beginInclusiveId; + private final long endExclusiveId; + + public ExpireSnapshotsPlan( + List<SnapshotExpireTask> dataFileTasks, + List<SnapshotExpireTask> changelogFileTasks, + List<SnapshotExpireTask> manifestTasks, + List<SnapshotExpireTask> snapshotFileTasks, + ProtectionSet protectionSet, + long beginInclusiveId, + long endExclusiveId) { + this.dataFileTasks = dataFileTasks; + this.changelogFileTasks = changelogFileTasks; + this.manifestTasks = manifestTasks; + this.snapshotFileTasks = snapshotFileTasks; + this.protectionSet = protectionSet; + this.beginInclusiveId = beginInclusiveId; + this.endExclusiveId = endExclusiveId; + } + + public static ExpireSnapshotsPlan empty() { + return EMPTY; + } + + public boolean isEmpty() { + return dataFileTasks.isEmpty() + && changelogFileTasks.isEmpty() + && manifestTasks.isEmpty() + && snapshotFileTasks.isEmpty(); + } + + /** Get data file deletion tasks (Phase 1a). These can be executed in parallel. */ + public List<SnapshotExpireTask> dataFileTasks() { + return dataFileTasks; + } + + /** Get changelog file deletion tasks (Phase 1b). These can be executed in parallel. */ + public List<SnapshotExpireTask> changelogFileTasks() { + return changelogFileTasks; + } + + /** Get manifest deletion tasks (Phase 2a). These should be executed serially. */ + public List<SnapshotExpireTask> manifestTasks() { + return manifestTasks; + } + + /** Get snapshot file deletion tasks (Phase 2b). These should be executed serially. */ + public List<SnapshotExpireTask> snapshotFileTasks() { + return snapshotFileTasks; + } + + /** + * Partition tasks into groups by snapshot ID range for parallel mode execution. + * + * <p>Each group contains tasks for a contiguous range of snapshots, with dataFileTasks first, + * then changelogFileTasks. This ensures: + * + * <ul> + * <li>Same snapshot range tasks are processed by the same worker + * <li>Within each worker, data files are deleted before changelog files + * </ul> + * + * <p>For example, with beginInclusiveId=1, endExclusiveId=11, parallelism=3: + * + * <ul> + * <li>Worker 0 (snapshot 1-4): [dataTask(2,3,4), changelogTask(1,2,3,4)] + * <li>Worker 1 (snapshot 5-8): [dataTask(5,6,7,8), changelogTask(5,6,7,8)] + * <li>Worker 2 (snapshot 9-11): [dataTask(9,10,11), changelogTask(9,10)] + * </ul> + * + * @param parallelism target parallelism for distribution + * @return list of task groups, one per worker + */ + public List<List<SnapshotExpireTask>> partitionTasksBySnapshotRange(int parallelism) { Review Comment: The simplified approach (env.fromSequence + flatMap) has two main issues: 1. Gap problem: Parallel deletion could leave gaps in snapshot history (e.g., 1, 3, 5 exist but 2, 4 are deleted), which is confusing for users. 2. Cache locality: Adjacent snapshots typically share the same nearest tag. Range partitioning allows each subtask to reuse createDataFileSkipperForTags cache, while dynamic fetching would scatter snapshots and break this benefit. See my response in comment#2 for more details. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
