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Guozhang Wang commented on KAFKA-7497: -------------------------------------- >From the expressiveness of the operators, I think there are cases of stream >self-join that cannot be captured with stream aggregations still, since the >window is really "sliding" (but if we add a sliding window type aggregations, >it may equal to the semantics of streams self-join). >From the API point of view, I think allowing stream self join even assuming >its use cases can be captured with sliding window aggregations still provides >programmability benefits. But the underlying implementation should be >different to any of our current internal impls. I think we can still have an >umbrella KIP that includes the following: 1. Add sliding window based aggregations. 2. Allow windowed stream self-join; and when detected it convert it to a sliding window based aggregation behind the scene for efficient implementations. > Kafka Streams should support self-join on streams > ------------------------------------------------- > > Key: KAFKA-7497 > URL: https://issues.apache.org/jira/browse/KAFKA-7497 > Project: Kafka > Issue Type: New Feature > Components: streams > Reporter: Robin Moffatt > Priority: Major > Labels: needs-kip > > There are valid reasons to want to join a stream to itself, but Kafka Streams > does not currently support this ({{Invalid topology: Topic foo has already > been registered by another source.}}). To perform the join requires creating > a second stream as a clone of the first, and then doing a join between the > two. This is a clunky workaround and results in unnecessary duplication of > data. -- This message was sent by Atlassian JIRA (v7.6.3#76005)