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https://issues.apache.org/jira/browse/FLINK-7169?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16119862#comment-16119862
 ] 

ASF GitHub Bot commented on FLINK-7169:
---------------------------------------

Github user dawidwys commented on a diff in the pull request:

    https://github.com/apache/flink/pull/4331#discussion_r132139143
  
    --- Diff: 
flink-libraries/flink-cep/src/main/java/org/apache/flink/cep/nfa/NFA.java ---
    @@ -322,6 +336,64 @@ public void resetNFAChanged() {
     
                }
     
    +           Set<T> discardEvents = new HashSet<>();
    +           switch(afterMatchSkipStrategy.getStrategy()) {
    +                   case SKIP_TO_LAST:
    +                           for (Map<String, List<T>> resultMap: result) {
    +                                   boolean matched = false;
    +                                   for (String key: resultMap.keySet()) {
    +                                           if 
(key.equals(afterMatchSkipStrategy.getPatternName())) {
    +                                                   matched = true;
    +                                                   
discardEvents.addAll(resultMap.get(key).subList(0, resultMap.get(key).size() - 
1));
    +                                           } else if (!matched) {
    +                                                   
discardEvents.addAll(resultMap.get(key));
    +                                           }
    +                                   }
    +                           }
    +                           break;
    +                   case SKIP_TO_FIRST:
    +                           for (Map<String, List<T>> resultMap: result) {
    --- End diff --
    
    similar as above


> Support AFTER MATCH SKIP function in CEP library API
> ----------------------------------------------------
>
>                 Key: FLINK-7169
>                 URL: https://issues.apache.org/jira/browse/FLINK-7169
>             Project: Flink
>          Issue Type: Sub-task
>          Components: CEP
>            Reporter: Yueting Chen
>            Assignee: Yueting Chen
>             Fix For: 1.4.0
>
>
> In order to support Oracle's MATCH_RECOGNIZE on top of the CEP library, we 
> need to support AFTER MATCH SKIP function in CEP API.
> There're four options in AFTER MATCH SKIP, listed as follows:
> 1. AFTER MATCH SKIP TO NEXT ROW: resume pattern matching at the row after the 
> first row of the current match.
> 2. AFTER MATCH SKIP PAST LAST ROW: resume pattern matching at the next row 
> after the last row of the current match.
> 3. AFTER MATCH SKIP TO FIST *RPV*: resume pattern matching at the first row 
> that is mapped to the row pattern variable RPV.
> 4. AFTER MATCH SKIP TO LAST *RPV*: resume pattern matching at the last row 
> that is mapped to the row pattern variable RPV.
> I think we can introduce a new function to `CEP` class, which takes a new 
> parameter as AfterMatchSKipStrategy.
> The new API may looks like this
> {code}
> public static <T> PatternStream<T> pattern(DataStream<T> input, Pattern<T, ?> 
> pattern, AfterMatchSkipStrategy afterMatchSkipStrategy) 
> {code}
> We can also make `SKIP TO NEXT ROW` as the default option, because that's 
> what CEP library behaves currently.



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