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From "Till Rohrmann (JIRA)" <j...@apache.org>
Subject [jira] [Created] (FLINK-3703) Add sequence matching semantics to discard matched events
Date Tue, 05 Apr 2016 12:21:25 GMT
Till Rohrmann created FLINK-3703:
------------------------------------

             Summary: Add sequence matching semantics to discard matched events
                 Key: FLINK-3703
                 URL: https://issues.apache.org/jira/browse/FLINK-3703
             Project: Flink
          Issue Type: Improvement
          Components: CEP
    Affects Versions: 1.0.0, 1.1.0
            Reporter: Till Rohrmann
            Priority: Minor


There is no easy way to decide whether events can be part of multiple matching sequences or
not. Currently, the default is that an event can participate in multiple matching sequences.
E.g. if you have the pattern {{Pattern.<Event>begin("a").followedBy("b")}} and the input
event stream {{Event("A"), Event("B"), Event("C")}}, then you will generate the following
matching sequences: {{Event("A"), Event("B")}}, {{Event("A"), Event("C")}} and {{Event("B"),
Event("C")}}. 

It would be useful to allow the user to define where the matching algorithm should continue
after a matching sequence has been found. Possible option values could be 
 * {{from first}} - continue keeping all events for future matches (that is the current behaviour)

 * {{after first}} -  continue after the first element (remove first matching event and continue
with the second event)
 * {{after last}} - continue after the last element (effectively discarding all elements of
the matching sequence)



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