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Posted to dev@kafka.apache.org by "Matthias J. Sax (JIRA)" <ji...@apache.org> on 2018/03/19 16:31:00 UTC

[jira] [Created] (KAFKA-6687) Allow to read a topic multiple times

Matthias J. Sax created KAFKA-6687:
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             Summary: 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


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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