[jira] [Commented] (FLINK-4169) CEP Does Not Work with RocksDB StateBackend

["Robert Metzger (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-4169?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15366088#comment-15366088 ] 

Robert Metzger commented on FLINK-4169:
---------------------------------------

Adding rocksdb as test-scoped dependency to the CEP library should not be an issue.

> CEP Does Not Work with RocksDB StateBackend
> -------------------------------------------
>
>                 Key: FLINK-4169
>                 URL: https://issues.apache.org/jira/browse/FLINK-4169
>             Project: Flink
>          Issue Type: Bug
>          Components: CEP
>    Affects Versions: 1.0.0, 1.1.0, 1.0.1, 1.0.2, 1.0.3
>            Reporter: Aljoscha Krettek
>            Assignee: Aljoscha Krettek
>            Priority: Blocker
>
> A job will never match any patterns because {{ValueState.update()}} is not called in the keyed CEP operators for updating the {{NFA}} state and the priority queue state.
> The reason why it works for other state backends is that they are very lax in their handling of state: if the object returned from {{ValueState.value())}} is mutable changes to this will be reflected in checkpoints even if {{ValueState.update()}} is not called. RocksDB, on the other hand, does always deserialize/serialize state values when accessing/updating them, so changes to the returned object will not be reflected in the state unless {{update()}} is called.
> We should fix this and also add a test for it. This might be tricky because we have to pull together RocksDB and CEP.



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