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https://issues.apache.org/jira/browse/KAFKA-5836?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16206353#comment-16206353
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Andy Chambers commented on KAFKA-5836:
--------------------------------------
Ah sorry. Not KS of course but the confluent AvroSerializer which registers the
schema as "[topic-name]-value". So to be completely concrete, the example below
represents some pseudo-code for building a couple of small topologies. It
demonstrates the scenario of wanting to evolve from v1 to v2 of some app. It is
assumed that all topics use the confluent schema registry's builtin
KafkaAvroSerializer for serialization. And that backwards-compatibility
checking is enabled on the schema registry. Topic "a" expects messages from
schema "a", topic "b" expects messages from schema "b" etc...
In app-v1:
a = topic-in(a)
b = topic-in(b)
result = window-join(a, b) # implicitly creates topics for each of the input
topics named
#
"${applicationId}-storeName-changelog" and because we're
# using avro+schema-registry, we get
corresponding subjects
# of the same name in the schema
registry. Lets say that in this
# case, we get implicit topics where
#
storeName=window-join-0001-changelog (holds topic a)
#
storeName=window-join-0002-changelog (holds topic b)
In app-v2:
a = topic-in(a)
b = topic-in(b)
# add some unrelated stuff to the topology but since it's a window join, in
the same position
# as the previous window the internal topics are the same but the topics
involved in this join
# are different. So now we have
# storeName=window-join-0001-changelog (holds topic c)
# storeName=window-join-0002-changelog (holds topic d)
# When the KafkaAvroSerializer tries to serialize messages destined for these
internal topics
# it will fail because the schema registry is expecting messages adhering to
schema a/b but
# will actually get messages matching schema c/d. The serializer will attempt
to register the
# the "new" schemas and fail because they are not "backward compatible" with
a/b.
window-join(topic-in(c), topic-in(d))
.foreach(spam-logs)
result = window-join(a, b)
> Kafka Streams - API for specifying internal stream name on join
> ---------------------------------------------------------------
>
> Key: KAFKA-5836
> URL: https://issues.apache.org/jira/browse/KAFKA-5836
> Project: Kafka
> Issue Type: New Feature
> Components: streams
> Affects Versions: 0.11.0.0
> Reporter: Lovro Pandžić
> Labels: api, needs-kip
>
> Automatic topic name can be problematic in case of streams operation
> change/migration.
> I'd like to be able to specify name of an internal topic so I can avoid
> creation of new stream and data "loss" when changing the Stream building.
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