Re: Streams group final result: EmitStrategy vs Suppressed

The main difference is the internal implementation. Semantically, both
are equivalent.

suppress() uses an in-memory buffer, while `emitStrategy()` does not,
but modifies the upstream aggregation operator impl, and waits to send
results downstream, and thus, it's RocksDB based.


-Matthias


On 4/12/24 10:37 AM, Ayoub wrote:
> Hello,
>
> *[Not sure if my email went through as I was not subscribed to this mailing
> list. Here is my original email]*
>
> I found that there are two ways to send only the final result of a windowed
> groupBy, either using Suppressed
> <https://kafka.apache.org/37/javadoc/org/apache/kafka/streams/kstream/KTable.html#suppress(org.apache.kafka.streams.kstream.Suppressed)>.untilWindowCloses
> on the final KTable or EmitStrategy
> <https://kafka.apache.org/37/javadoc/org/apache/kafka/streams/kstream/TimeWindowedKStream.html#emitStrategy(org.apache.kafka.streams.kstream.EmitStrategy)>
> on
> the windowed stream.
>
> I tried to compare both but didn't find differences in the result they give.
>
> Are there any differences apart from the moment they are defined within the
> pipeline. And is there any preference on using one or the other ?
>
> Thanks,
> Ayoub
>
>
> Le ven. 12 avr. 2024 à 11:50, Ayoub <ayoubomari96@gmail.com> a écrit :
>
>> Hello,
>>
>> I found that there are two ways to send only the final result of a
>> windowed groupBy, either using Suppressed
>> <https://kafka.apache.org/37/javadoc/org/apache/kafka/streams/kstream/KTable.html#suppress(org.apache.kafka.streams.kstream.Suppressed)>.untilWindowCloses
>> on the final KTable or EmitStrategy
>> <https://kafka.apache.org/37/javadoc/org/apache/kafka/streams/kstream/TimeWindowedKStream.html#emitStrategy(org.apache.kafka.streams.kstream.EmitStrategy)> on
>> the windowed stream.
>>
>> I tried to compare both but didn't find differences in the result they
>> give.
>>
>> Are there any differences apart from the moment they are defined within
>> the pipeline. And Is there any preference on using one or the other ?
>>
>> Thanks,
>> Ayoub
>>
>