FlinkCEP: pattern application on a KeyedStream

[Federico D'Ambrosio]

Hi all,

I was wondering if it is correct to assume the application of a pattern on a KeyedStream similar to the application, e.g., of a MapFunction when it comes to state.

For example, the following

val pattern = ...

val keyedStream = stream.keyBy("id")

val patternKeyedStream = CEP.pattern(pattern, keyedStream)

val anotherKeyedStream = patternKeyedStream.select(...)

should only check the pattern on each single partition value.

Am I correct in assuming this, or I have misunderstood CEP functioning?

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[Kostas Kloudas]

Hi Federico,

If I understand your question correctly, then yes, the application of a Pattern on a keyed stream 

is similar to the application of a map function.

It will search for the pattern on each per-key stream of data.

So there will be state (buffer with partial matches, queued elements, etc) for every active key.

Cheers,

Kostas

On Oct 19, 2017, at 11:55 AM, Federico D'Ambrosio <[hidden email]> wrote:

Hi all,

I was wondering if it is correct to assume the application of a pattern on a KeyedStream similar to the application, e.g., of a MapFunction when it comes to state.

For example, the following

val pattern = ...

val keyedStream = stream.keyBy("id")

val patternKeyedStream = CEP.pattern(pattern, keyedStream)

val anotherKeyedStream = patternKeyedStream.select(...)

should only check the pattern on each single partition value.

Am I correct in assuming this, or I have misunderstood CEP functioning?

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