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https://issues.apache.org/jira/browse/FLINK-18263?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17195961#comment-17195961
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Yun Tang commented on FLINK-18263:
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After state processor API introduced and Flink-14942 resolved, I think we could 
offer user more freedom to play with retained checkpoint no matter for 
bootstrap or other targets. I think we could introduce anther new 
CheckpointRetentionPolicy named {{ALWAYS_RETAIN_AFTER_TERMINATION}} for expert 
users and keep most of code stay the same to not introduce big change.
Moreover, we should warn user that {{ALWAYS_RETAIN_AFTER_TERMINATION}} 
retention policy could lead more space usage left and must be cautious to use 
this with in time external clean up.

What do you think of this suggestion? [~markcho]

> Allow external checkpoints to be persisted even when the job is in "Finished" 
> state.
> ------------------------------------------------------------------------------------
>
>                 Key: FLINK-18263
>                 URL: https://issues.apache.org/jira/browse/FLINK-18263
>             Project: Flink
>          Issue Type: Improvement
>          Components: Runtime / Checkpointing
>            Reporter: Mark Cho
>            Priority: Major
>              Labels: pull-request-available
>
> Currently, `execution.checkpointing.externalized-checkpoint-retention` 
> configuration supports two options:
> - `DELETE_ON_CANCELLATION` which keeps the externalized checkpoints in FAILED 
> and SUSPENDED state.
> - `RETAIN_ON_CANCELLATION` which keeps the externalized checkpoints in 
> FAILED, SUSPENDED, and CANCELED state.
> This gives us control over the retention of externalized checkpoints in all 
> terminal state of a job, except for the FINISHED state.
> If the job ends up in "FINISHED" state, externalized checkpoints will be 
> automatically cleaned up and there currently is no config that will ensure 
> that these externalized checkpoints to be persisted.
> I found an old Jira ticket FLINK-4512 where this was discussed. I think it 
> would be helpful to have a config that can control the retention policy for 
> FINISHED state as well.
> - This can be useful for cases where we want to rewind a job (that reached 
> the FINISHED state) to a previous checkpoint.
> - When we use externalized checkpoints, we want to fully delegate the 
> checkpoint clean-up to an external process in all job states (without 
> cherrypicking FINISHED state to be cleaned up by Flink).
> We have a quick fix working in our fork where we've changed 
> `ExternalizedCheckpointCleanup` enum:
> {code:java}
> RETAIN_ON_FAILURE (renamed from DELETE_ON_CANCELLATION; retains on FAILED)
> RETAIN_ON_CANCELLATION (kept the same; retains on FAILED, CANCELED)
> RETAIN_ON_SUCCESS (added; retains on FAILED, CANCELED, FINISHED)
> {code}
> Since this change requires changes to multiple components (e.g. config 
> values, REST API, Web UI, etc), I wanted to get the community's thoughts 
> before I invest more time in my quick fix PR (which currently only contains 
> minimal change to get this working).



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