Kafka, mail # user - Re: Partitioning and scale - 2013-05-22, 20:15
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Re: Partitioning and scale
- I see that Kafka server.properties allows one to specify the number of
partitions it supports. However, when we want to scale I wonder if we add #
of partitions or # of brokers, will the same partitioner start distributing
the messages to different partitions?
 And if it does, how can that same consumer continue to read off the
messages of those ids if it was interrupted in the middle?

The num.partitions config in server.properties is used only for topics that
are auto created (controlled by auto.create.topics.enable). For topics that
you create using the admin tool, you can specify the number of partitions
that you want. After that, currently there is no way to change that. For
that reason, it is a good idea to over partition your topic, which also
helps load balance partitions onto the brokers. You are right that if you
change the number of partitions later, then previously messages that stuck
to a certain partition would now get routed to a different partition, which
is undesirable for applications that want to use sticky partitioning.

- I'd like to create a consumer per partition, and for each one to
subscribe to the changes of that one. How can this be done in kafka?

For your use case, it seems like SimpleConsumer might be a better fit.
However, it will require you to write code to handle discovery of leader
for the partition that your consumer is consuming. Chris has written up a
great example that you can follow -
https://cwiki.apache.org/confluence/display/KAFKA/0.8.0+SimpleConsumer+Example

Thanks,
Neha
On Wed, May 22, 2013 at 12:37 PM, Chris Curtin <[EMAIL PROTECTED]>wrote:
 
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