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https://issues.apache.org/jira/browse/FLINK-4445?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15430336#comment-15430336
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Gyula Fora commented on FLINK-4445:
-----------------------------------

Hi Ufuk,

My personal experience is that it's very easy to run into mistakes when dealing 
with more complex stateful job such as forget uids on kafka source/sink and 
other built-in stateful operators.

Ignoring the unmatched state by default would be super dangerous and would have 
caused me serious issues in the past. I think adding a force ignore flag 
(option 1) would be the good way to go and is also very useful :)

Cheers,
Gyula 

> Ignore unmatched state when restoring from savepoint
> ----------------------------------------------------
>
>                 Key: FLINK-4445
>                 URL: https://issues.apache.org/jira/browse/FLINK-4445
>             Project: Flink
>          Issue Type: Improvement
>          Components: State Backends, Checkpointing
>    Affects Versions: 1.1.1
>            Reporter: Ufuk Celebi
>
> When currently submitting a job with a savepoint, we require that all state 
> is matched to the new job. Many users have noted that this is overly strict. 
> I would like to loosen this and allow savepoints to be restored without 
> matching all state.
> The following options come to mind:
> (1) Keep the current behaviour, but add a flag to allow ignoring state when 
> restoring, e.g. {{bin/flink -s <savepoint> --ignoreUnmatchedState}}. This 
> would be non-API breaking.
> (2) Ignore unmatched state and continue. Additionally add a flag to be strict 
> about checking the state, e.g. {{bin/flink -s <savepoint> --strict}}. This 
> would be API-breaking as the default behaviour would change. Users might be 
> confused by this because there is no straight forward way to notice that 
> nothing has been restored.
> I'm not sure what's the best thing here. [~gyfora], [~aljoscha] What do you 
> think?



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