pvary commented on code in PR #13853: URL: https://github.com/apache/iceberg/pull/13853#discussion_r2285227511
########## docs/docs/flink-table-maintenance.md: ########## @@ -0,0 +1,363 @@ +--- +title: "Flink Table Maintenance " +--- +<!-- + - 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. + --> + +# Flink Table Maintenance + +## Overview + +In **Apache Iceberg** deployments within **Flink streaming environments**, implementing automated table maintenance operations—including `snapshot expiration`, `small file compaction`, and `orphan file cleanup`—is critical for optimal query performance and storage efficiency. + +Traditionally, these maintenance operations were exclusively accessible through **Iceberg Spark Actions**, necessitating the deployment and management of dedicated Spark clusters. This dependency on **Spark infrastructure** solely for table optimization introduces significant **architectural complexity** and **operational overhead**. + +The `TableMaintenance` API in **Apache Iceberg** empowers **Flink jobs** to execute maintenance tasks **natively**, either embedded within existing streaming pipelines or deployed as standalone Flink jobs. This eliminates dependencies on external systems, thereby **streamlining architecture**, **reducing operational costs**, and **enhancing automation capabilities**. + +## Supported Features (Flink) + +### ExpireSnapshots +Removes old snapshots and their files. Internally uses `cleanExpiredFiles(true)` when committing, so expired metadata/files are cleaned up automatically. + +```java +.add(ExpireSnapshots.builder() + .maxSnapshotAge(Duration.ofDays(7)) + .retainLast(10) + .deleteBatchSize(1000)) +``` + +### RewriteDataFiles +Compacts small files to optimize file sizes. Supports partial progress commits and limiting maximum rewritten bytes per run. + +```java +.add(RewriteDataFiles.builder() + .targetFileSizeBytes(256 * 1024 * 1024) + .minFileSizeBytes(32 * 1024 * 1024) + .partialProgressEnabled(true) + .partialProgressMaxCommits(5)) +``` + +## Lock Management + +The `TriggerLockFactory` is essential for coordinating maintenance tasks across multiple Flink jobs or instances. It prevents concurrent maintenance operations on the same table, which could lead to conflicts or data corruption. Review Comment: ``` The `TriggerLockFactory` is essential for coordinating maintenance tasks. It prevents concurrent maintenance operations on the same table, which could lead to conflicts or data corruption. ``` The multiple instances of the same tasks could conflict even when only a single compaction job is running. Maybe we should add something along this line too -- 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: issues-unsubscr...@iceberg.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@iceberg.apache.org For additional commands, e-mail: issues-h...@iceberg.apache.org
