CODEWITHSUNDEEP
apache-flink
Tom
Tom

Reputation: 6332

Difference between savepoint and checkpoint in Flink

I know there are similar questions on the stackoverflow,but after investigating several of them, I know

  1. savepoint is triggered manually, while checkpoint is triggered automatically

  2. They are using different storage format

But these are not the confusing points,I have no idea when to use one or when to use the other.

Consider the following two scenarios:

  1. If I need to shutdown or restart the whole application for some reason(eg bug fix or crash unexpected) , then I will have to use savepoint to restore the whole application?
  2. I thought that checkpoint is only used internally in Flink for fault tolerance when application is running, that is, the application itself is running, but tasks or other things may fail， that is, Flink will use checkpoint for state recovery?
  3. There is also externalized checkpoint, I think it is the same with savepoint in functionality, that is, externalized checkpoint can also be used to recover from a restarted application?

Upvotes: 2

Views: 507

Answers (1)

Jiayi Liao
Jiayi Liao

Reputation: 1009

Does Flink use checkpoint for state recovery?

Basically you're right. As you said, the checkpoint is usually used internally in Flink for fault tolerance and it's more like a concept inside the framework. When your application fails, the program will try to restart from the latest checkpoint. That's how checkpoint works in Flink, without any mannual interfering.

Should I use savepoint to restore the whole application for bug fix?

Yes. In these cases, you don't want to restore from the checkpoint because maybe the latest checkpoint occurs several minutes ago. Instead, you'd like to snapshot the current the state of the whole application and restart it from the latest savepoint, which may be the quickest way to restore the application without too much delay.

Externalized checkpoint.

It's still the checkpoint, but will be persisted externally based on your configurations. It can be used to restore the application, but the states are not so real time because there exists an interval between checkpoints.

For more information, take a look at this blog artical: https://data-artisans.com/blog/differences-between-savepoints-and-checkpoints-in-flink.

Upvotes: 2

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