[
https://issues.apache.org/jira/browse/KAFKA-3705?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16816656#comment-16816656
]
Adam Bellemare edited comment on KAFKA-3705 at 4/12/19 9:05 PM:
----------------------------------------------------------------
The PR is now in a draft state - there are a few issues yet to be resolved, but
they are detailed within the PR. Please take a look at provide any feedback
that you can.
https://github.com/apache/kafka/pull/5527
was (Author: abellemare):
The PR is now in a draft state - there are a few issues yet to be resolved, but
they are detailed within the PR. Please take a look at provide any feedback
that you can.
> Support non-key joining in KTable
> ---------------------------------
>
> Key: KAFKA-3705
> URL: https://issues.apache.org/jira/browse/KAFKA-3705
> Project: Kafka
> Issue Type: New Feature
> Components: streams
> Reporter: Guozhang Wang
> Assignee: Adam Bellemare
> Priority: Major
> Labels: api, kip
>
> KIP-213:
> [https://cwiki.apache.org/confluence/display/KAFKA/KIP-213+Support+non-key+joining+in+KTable]
> 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:java}
> 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
(v7.6.3#76005)
