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https://issues.apache.org/jira/browse/FLINK-9576?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16571317#comment-16571317
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ASF GitHub Bot commented on FLINK-9576:
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dawidwys commented on a change in pull request #6268: [FLINK-9576] Fixed
documentation for contiguity within looping pattern.
URL: https://github.com/apache/flink/pull/6268#discussion_r208154095
##########
File path: docs/dev/libs/cep.md
##########
@@ -919,6 +774,164 @@ next.within(Time.seconds(10))
</div>
</div>
+#### Contiguity within looping patterns
+
+You can apply the same contiguity condition as discussed in the previous
[section](#combining-patterns) within a looping pattern.
+The contiguity will be applied between elements accepted into such a pattern.
+To illustrate the above with an example, a pattern sequence `"a b+ c"` (`"a"`
followed by one or more `"b"`'s followed by a `"c"`) with
+input `"a", "b1", "d1", "b2", "d2", "b3" "c"` will have the following results:
+
+ 1. **Strict Contiguity**: `{a b3}` -- the `"d1"` after `"b1"` causes `"b1"`
to be discarded, the same happens for `"b2"` because of `"d2"`.
+
+ 2. **Relaxed Contiguity**: `{a b1 c}`, `{a b1 b2 c}`, `{a b1 b2 b3 c}` --
`"d"`'s are ignored.
+
+ 3. **Non-Deterministic Relaxed Contiguity**: `{a b1 c}`, `{a b1 b2 c}`, `{a
b1 b3 c}`, `{a b1 b2 b3 c}` - notice the `{a b1 b3 c}`, which is the result of
Review comment:
Actually I've updated pattern in this example with different contiguity
between `a` and `b+` cause otherwise the example for strict contiguity was
wrong.
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> Wrong contiguity documentation
> ------------------------------
>
> Key: FLINK-9576
> URL: https://issues.apache.org/jira/browse/FLINK-9576
> Project: Flink
> Issue Type: Bug
> Components: CEP, Documentation
> Reporter: Dawid Wysakowicz
> Assignee: Dawid Wysakowicz
> Priority: Critical
> Labels: pull-request-available
> Fix For: 1.6.0
>
>
> Example for the contiguity is first of all wrong, and second of all
> misleading:
>
> {code:java}
> To illustrate the above with an example, a pattern sequence "a+ b" (one or
> more "a"’s followed by a "b") with input "a1", "c", "a2", "b" will have the
> following results:
> Strict Contiguity: {a2 b} – the "c" after "a1" causes "a1" to be discarded.
> Relaxed Contiguity: {a1 b} and {a1 a2 b} – "c" is ignored.
> Non-Deterministic Relaxed Contiguity: {a1 b}, {a2 b}, and {a1 a2 b}.
> For looping patterns (e.g. oneOrMore() and times()) the default is relaxed
> contiguity. If you want strict contiguity, you have to explicitly specify it
> by using the consecutive() call, and if you want non-deterministic relaxed
> contiguity you can use the allowCombinations() call.
> {code}
>
> Results for the relaxed contiguity are wrong plus they do not clearly
> explains the internal contiguity of kleene closure.
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