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https://issues.apache.org/jira/browse/KAFKA-1119?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13813655#comment-13813655
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Jay Kreps commented on KAFKA-1119:
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Hmm, but it looks like the current behavior is to just blindly set whatever
properties are given on the command line as the FULL set of properties. So if I
say
./bin/kafka-topics.sh --alter --config retention.ms=180000
I might think I am just changing the retention.ms but in reality I am unsetting
any previous per-topic configs (whatever they may be) and setting retention.ms.
Currently the code looks like this:
val configs = parseTopicConfigs(opts)
AdminUtils.changeTopicConfig(zkClient, topic, configs)
I think it might be more intuitive if we interpreted the args as a diff to
apply to the current settings. So the code would be soemthing like:
val configs = AdminUtils.fetchTopicConfig(zkClient, topic)
configs.addAll(parseTopicConfigs(opts))
AdminUtils.changeTopicConfig(zkClient, topic, configs)
This does have a downside, though. How do you remove an override? Let's say
there is a default of X, setting X actually sets a topic override of X which is
different from having no setting for the config (because if you change the
default that topic would be unaffected). This is not hugely important but some
options for handling this would be
1. No value means delete the config: --config x=
2. Add a new option for unconfiguring: --config x=12 and --unconfig x
> Kafka 0.8.1 overwrites previous per topic config changes
> --------------------------------------------------------
>
> Key: KAFKA-1119
> URL: https://issues.apache.org/jira/browse/KAFKA-1119
> Project: Kafka
> Issue Type: Bug
> Components: config
> Affects Versions: 0.8.1
> Reporter: Neha Narkhede
> Assignee: Neha Narkhede
> Priority: Blocker
>
> kafka-topics --alter --config overwrites the previous per topic configs.
> There is no way to override more than one per topic config for the same topic
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