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From tao xiao <xiaotao...@gmail.com>
Subject Re: Specify leader when doing partition reassignment
Date Wed, 05 Aug 2015 14:12:45 GMT
Thank you Todd for the detailed answer
On Wed, Aug 5, 2015 at 9:09 PM Todd Palino <tpalino@gmail.com> wrote:

> To make sure you have a complete answer here, the order of the replica list
> that you specify in the partition reassignment will affect the leader
> selection, but if the current leader is in the new replica list, it will
> not change the leadership to change.
>
> That is, if your current replica list is [1, 2] and the leader is 1, and
> you change the replica list to [3, 1] nothing happens immediately except
> that 2 is removed as a replica and 3 is added. Upon a failure of broker 1
> or a preferred replica election, broker 3 will take over leadership. If the
> new replica list is [3, 4], then upon completion of the reassignment,
> broker 3 will be selected as the new leader.
>
> The controller will prefer to select the first broker in the replica list
> as the leader. This means that if you do a partition reassignment and
> change the replica list from [1, 2] to [2, 1], nothing happens at first.
> But upon the next preferred replica election, broker 2 will be selected as
> the leader.
>
> -Todd
>
>
> On Wed, Aug 5, 2015 at 3:37 AM, tao xiao <xiaotao183@gmail.com> wrote:
>
> > I think I figured it out. As pointed out in
> >
> >
> https://cwiki.apache.org/confluence/display/KAFKA/Replication+tools#Replicationtools-6.ReassignPartitionsTool
> >
> > If the leader is not in the reassigned replica a new leader will be
> elected
> > and the tool doesn't pick the first one from the RAR as the leader
> >
> > On Wed, 5 Aug 2015 at 18:32 Jilin Xie <jilinxie1988@gmail.com> wrote:
> >
> > > Check the --replica-assignment  parameter of the kafka-topics.sh.
> > > It does what you need.
> > > And there should also be similar configs in the api if you wanna do so
> by
> > > coding.
> > >
> > > On Wed, Aug 5, 2015 at 6:18 PM, tao xiao <xiaotao183@gmail.com> wrote:
> > >
> > > > Hi team,
> > > >
> > > > Is it possible to specify a leader broker for each topic partition
> when
> > > > doing partition reassignment?
> > > >
> > > > For example I have following json. Is the first broker in the
> replicas
> > > list
> > > > by default the leader of the partition e.g. broker 3 is the leader of
> > > topic
> > > > test5 and broker 2 is the leader of topic test3. or does Kafka
> > > > automatically pick the leader based on the leadership ratio
> > > > if auto.leader.rebalance.enable is on
> > > >
> > > > {
> > > >   "version": 1,
> > > >   "partitions": [
> > > >     {
> > > >       "topic": "test5",
> > > >       "partition": 0,
> > > >       "replicas": [3, 1]
> > > >     },
> > > >     {
> > > >       "topic": "test3",
> > > >       "partition": 0,
> > > >       "replicas": [2,3]
> > > >     },
> > > >     {
> > > >       "topic": "test1",
> > > >       "partition": 0,
> > > >       "replicas": [1,2]
> > > >     }
> > > >   ]
> > > > }
> > > >
> > >
> >
>

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