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From "Ismael Juma (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (KAFKA-3234) Minor documentation edits: clarify minISR; some topic-level configs are missing
Date Wed, 25 Jan 2017 16:37:26 GMT

     [ https://issues.apache.org/jira/browse/KAFKA-3234?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Ismael Juma updated KAFKA-3234:
    Fix Version/s:     (was:

> Minor documentation edits: clarify minISR; some topic-level configs are missing
> -------------------------------------------------------------------------------
>                 Key: KAFKA-3234
>                 URL: https://issues.apache.org/jira/browse/KAFKA-3234
>             Project: Kafka
>          Issue Type: Improvement
>          Components: website
>            Reporter: Joel Koshy
>            Assignee: Joel Koshy
> Based on an offline conversation with [~junrao] and [~gwenshap]
> The current documentation is somewhat confusing on minISR in that it says that it offers
a trade-off between consistency and availability. From the user's view-point, consistency
(at least in the usual sense of the term) is achieved by disabling unclean leader election
- since no replica that was out of ISR can be elected as the leader. So a consumer will never
see a message that was not acknowledged to a producer that set acks to "all". Or to put it
another way, setting minISR alone will not prevent exposing uncommitted messages - disabling
unclean leader election is the stronger requirement. You can achieve the same effect though
by setting minISR equal to  the number of replicas.
> There is also some stale documentation that needs to be removed:
> {quote}
> In our current release we choose the second strategy and favor choosing a potentially
inconsistent replica when all replicas in the ISR are dead. In the future, we would like to
make this configurable to better support use cases where downtime is preferable to inconsistency.
> {quote}
> Finally, it was reported on the mailing list (from Elias Levy) that compression.type
should be added under the topic configs. Same goes for unclean leader election. Would be good
to have these auto-generated.

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