Status

Current state:  Under Discussion Adopted (2.0.0)

Discussion thread: TBD

JIRA: 

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This KIP would propose to add a single fetch API to the WindowedStoreWindowStore, and use that in the KStreamWindowedAggregate KStreamWindowAggregate / KStreamWindowedReduce KStreamWindowReduce operators.

ReadOnlyWindowStore interface

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1. For all implementations of the WindowedStore, including CachingWindowedStoreCachingWindowStore, RocksDBWindowedStoreRocksDBWindowStore, etc, add the implementations of this API for a single value lookup accordingly.
2. In KStreamWindowedAggregate and KStreamWindowedReduce, replace the "fetch(K, long start, long to)" with this newly added API.

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