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https://issues.apache.org/jira/browse/FLINK-20427?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17240904#comment-17240904
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Stephan Ewen commented on FLINK-20427:
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+1 to remove it, until the semantics we better defined.

I would also vote to deprecate/discourage it in 1.12 already.

> Remove CheckpointConfig.setPreferCheckpointForRecovery because it can lead to 
> data loss
> ---------------------------------------------------------------------------------------
>
>                 Key: FLINK-20427
>                 URL: https://issues.apache.org/jira/browse/FLINK-20427
>             Project: Flink
>          Issue Type: Bug
>          Components: API / DataStream, Runtime / Checkpointing
>    Affects Versions: 1.12.0
>            Reporter: Till Rohrmann
>            Priority: Critical
>             Fix For: 1.13.0
>
>
> The {{CheckpointConfig.setPreferCheckpointForRecovery}} allows to configure 
> whether Flink prefers checkpoints for recovery if the 
> {{CompletedCheckpointStore}} contains savepoints and checkpoints. This is 
> problematic because due to this feature, Flink might prefer older checkpoints 
> over newer savepoints for recovery. Since some components expect that the 
> always the latest checkpoint/savepoint is used (e.g. the 
> {{SourceCoordinator}}), it breaks assumptions and can lead to 
> {{SourceSplits}} which are not read. This effectively means that the system 
> loses data. Similarly, this behaviour can cause that exactly once sinks might 
> output results multiple times which violates the processing guarantees. 
> Hence, I believe that we should remove this setting because it changes 
> Flink's behaviour in some very significant way potentially w/o the user 
> noticing.



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