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Jay Kreps commented on KAFKA-3511: ---------------------------------- The issue is that there are dozens of common aggregation functions, which ones will be built in and which not? I would argue the other direction, why not remove countByKey and implement all of these as Aggregator implementations, so you would do something like: myStream.aggregateByKey(new Count(), <serdes>) > Provide built-in aggregators sum() and avg() in Kafka Streams DSL > ----------------------------------------------------------------- > > Key: KAFKA-3511 > URL: https://issues.apache.org/jira/browse/KAFKA-3511 > Project: Kafka > Issue Type: Bug > Components: kafka streams > Reporter: Guozhang Wang > Labels: newbie > Fix For: 0.10.0.0 > > > Currently we only have one built-in aggregate function count() in the Kafka > Streams DSL, but we want to add more aggregation functions like sum() and > avg(). -- This message was sent by Atlassian JIRA (v6.3.4#6332)