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Discussion thread: here [Change the link from the KIP proposal email archive to your own email thread]

JIRA: KAFKA-5636here

Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).

Motivation

Currently, Kafka Streams implements session windows, tumbling windows, and hopping windows as windowed aggregation methods. While hopping windows with a small advance time are similar to a sliding window, this implementation's performance is poor because it results in many overlapping and often redundant windows that require expensive calculations. As sliding windows do calculations for each distinct window, the sliding window implementation would be a more efficient way to do these types of aggregations. Additionally, sliding windows are inclusive on both the start and end time, creating a different set of windows than hopping windows, which are only inclusive on the start time.  

This KIP proposes adding sliding windows to give users an efficient way to do sliding aggregation. Describe the problems you are trying to solve.

Public Interfaces

Briefly list any new interfaces that will be introduced as part of this proposal or any existing interfaces that will be removed or changed. The purpose of this section is to concisely call out the public contract that will come along with this feature.

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