akalash commented on a change in pull request #18765: URL: https://github.com/apache/flink/pull/18765#discussion_r814858315
########## File path: docs/content/docs/ops/state/checkpoint_vs_savepoint.md ########## @@ -0,0 +1,86 @@ +--- +title: "Checkpoint VS Savepoint" +weight: 10 +type: docs +aliases: + - /ops/state/checkpoint_vs_savepoint.html +--- +<!-- +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. +--> + +# Checkpoint VS Savepoint + +## Overview + +Conceptually, Flink's [Savepoints]({{< ref "docs/ops/state/savepoints" >}}) are different from [Checkpoints]({{< ref "docs/ops/state/checkpoints" >}}) +in a similar way that backups are different from recovery logs in traditional database systems. +The primary purpose of Checkpoints is to provide a recovery mechanism in case of unexpected job failures. +A [Checkpoint's lifecycle]({{< ref "docs/dev/datastream/fault-tolerance/checkpointing" >}}) is managed by Flink, +i.e. a Checkpoint is created, owned, and released by Flink - without user interaction. +As a method of recovery and being periodically triggered, two main design goals for the Checkpoint implementation are +i) being as lightweight to create and ii) being as fast to restore from as possible. +Optimizations towards those goals can exploit certain properties, e.g. that the job code doesn't change between the execution attempts. +Checkpoints are usually dropped after the job was terminated by the user (except if explicitly configured as retained Checkpoints). + +In contrast to all this, Savepoints are created, owned, and deleted by the user. +Their use-case is for planned, manual backup and resume. For example, this could be an update of your Flink version, changing your job graph, +changing parallelism, forking a second job like for a red/blue deployment, and so on. +Of course, Savepoints must survive job termination. Conceptually, Savepoints can be a bit more expensive +to produce and restore and focus more on portability and support for the previously mentioned changes to the job. + +### The main checkpoint differences + +[Checkpoints]({{< ref "docs/ops/state/checkpoints" >}}) have a few differences from [savepoints]({{< ref "docs/ops/state/savepoints" >}}). They +- use a state backend specific (low-level) data format, may be incremental. (starting from Flink 1.15 savepoints can also use the backend [native]({{< ref "docs/ops/state/savepoints" >}}#savepoint-format) format.) +- do not support Flink specific features like rescaling. Review comment: I am not really sure that it is true now. -- 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...@flink.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
