[jira] [Commented] (FLINK-7292) Fix EMPTY MATCH bug in CEP.

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

    [ https://issues.apache.org/jira/browse/FLINK-7292?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16193122#comment-16193122 ] 

Kostas Kloudas commented on FLINK-7292:
---------------------------------------

Hi [~litrain_1],

I believe that for infinite streams, an empty result does not make much sense. Conceptually, the empty result means that "there is no match in your input". If the input in infinite, this becomes "there is no match in your input *so far* " and given that this "so far" is not defined, it would mean that we have infinite "no matches" between potential matches. Even if we integrated it, this would imply a waste of resources, as we would have to iterate over all keys, and for each one emit an "empty match" element.

Given the above, for the sake of having a clean JIRA and given that this discussion seems stale, I would recommend closing this issue. 

If nobody objects till Monday, I will close it. 
Please let me know if you disagree.

> Fix EMPTY MATCH bug in CEP.
> ---------------------------
>
>                 Key: FLINK-7292
>                 URL: https://issues.apache.org/jira/browse/FLINK-7292
>             Project: Flink
>          Issue Type: Sub-task
>          Components: CEP
>            Reporter: zhangxiaoyu
>
> Currently, with the pattern {quote}a? {quote}and the event{quote} a1{quote}, the result pattern is only{quote} a1{quote}without the empty match.
> We wish the empty matched is also returned. And I am working on this issue now.
> My method is  checking if there exists empty match only when the the first event comes(at the StartState) ——try to traverse the PROCEED edges with the trueFunction condition from the StartState, see if it can arrive FinalState, if so, add an empty list to the result.



--
This message was sent by Atlassian JIRA
(v6.4.14#64029)