[
https://issues.apache.org/jira/browse/KAFKA-3705?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15396508#comment-15396508
]
Guozhang Wang commented on KAFKA-3705:
--------------------------------------
Yeah currently we do not have a windowed-stream table join, and hence the
stream is not materialized but only the table. We can add this join type though
in the next release if we feel it is a common request.
> Support non-key joining in KTable
> ---------------------------------
>
> Key: KAFKA-3705
> URL: https://issues.apache.org/jira/browse/KAFKA-3705
> Project: Kafka
> Issue Type: Bug
> Components: streams
> Reporter: Guozhang Wang
> Assignee: Liquan Pei
> Labels: api
> Fix For: 0.10.1.0
>
>
> Today in Kafka Streams DSL, KTable joins are only based on keys. If users
> want to join a KTable A by key {{a}} with another KTable B by key {{b}} but
> with a "foreign key" {{a}}, and assuming they are read from two topics which
> are partitioned on {{a}} and {{b}} respectively, they need to do the
> following pattern:
> {code}
> tableB' = tableB.groupBy(/* select on field "a" */).agg(...); // now tableB'
> is partitioned on "a"
> tableA.join(tableB', joiner);
> {code}
> Even if these two tables are read from two topics which are already
> partitioned on {{a}}, users still need to do the pre-aggregation in order to
> make the two joining streams to be on the same key. This is a draw-back from
> programability and we should fix it.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
