[jira] [Commented] (FLINK-6939) Not store IterativeCondition with NFA state

["Kostas Kloudas (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-6939?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16062398#comment-16062398 ] 

Kostas Kloudas commented on FLINK-6939:
---------------------------------------

Hi [~jark], I reviewed your PR and have some comments on the code itself, but before publishing them I would like to understand the need of this change. 

Although it seems nice, and, in general, I liked the code,  the problem is that it is not aligned with another change that we have in the pipeline, which is dynamically adding patterns to the CEP operator. In a nutshell, you can imagine a co-stream where the patterns will come from, and then be translated into NFAs and be stored. In this case, not storing the conditions can result in problems, as the Patterns are not hardcoded in the program anymore, and they cannot be necessarily re-produced upon recovery. 

We may be able to find a middle ground, where conditions are not always serialized and de-serialized, but they are still stored upon creation of the NFA, but before going down this road, could you please explain me a bit if this is just an optimization or it serves any other purpose?

> Not store IterativeCondition with NFA state
> -------------------------------------------
>
>                 Key: FLINK-6939
>                 URL: https://issues.apache.org/jira/browse/FLINK-6939
>             Project: Flink
>          Issue Type: Sub-task
>          Components: CEP
>            Reporter: Jark Wu
>            Assignee: Jark Wu
>             Fix For: 1.4.0
>
>
> Currently, the IterativeCondition is stored with the total NFA state. And de/serialized every time when update/get the NFA state. It is a heavy operation and not necessary. In addition it is a required feature for FLINK-6938.



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