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https://issues.apache.org/jira/browse/KAFKA-6687?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16530668#comment-16530668
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Richard Yu commented on KAFKA-6687:
-----------------------------------
It appears that the summary and the description is somewhat contradictory:
while the summary states that we should "allow a topic to be read multiple
times", in the description it states that "we should allow adding a topic
multiple times and rewrite the topology internally so that it can be read
*only* once." Which one is it?
> Allow to read a topic multiple times
> ------------------------------------
>
> Key: KAFKA-6687
> URL: https://issues.apache.org/jira/browse/KAFKA-6687
> Project: Kafka
> Issue Type: Improvement
> Components: streams
> Reporter: Matthias J. Sax
> Priority: Major
>
> Users often want to read topic multiple times. However, this is not possible
> because there is a single consumer and thus a topic can only be consumed once.
> Users get an exception
> {quote}Exception in thread “main”
> org.apache.kafka.streams.errors.TopologyException: Invalid topology: Topic
> source has already been registered by another source.
> {quote}
> If they use a topic name in multiple `stream()`, `table()`, `globalTable()`
> calls.
> However, with KAFKA-6034 in place, we could allow adding a topic multiple
> times and rewrite the topology internally to only read the topic once. This
> would simplify application code as users don't need to put workaround in
> place to get the same behavior.
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