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From: Benjamin Black <b@b3k.us>
Date: Sun, 6 Oct 2013 19:06:59 -0700
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Subject: Re: Managing Millions of Paritions in Kafka
To: users@kafka.apache.org
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Ha ha, yes, exactly, you need a database. Kafka is a wonderful tool, but
not the right one for a job like that.


On Sun, Oct 6, 2013 at 7:03 PM, Ravindranath Akila <
ravindranathakila@gmail.com> wrote:

> Actually, we need a broker. But a more stateful one. Hence the decision to
> use TTL on hbase.
> On 7 Oct 2013 08:38, "Benjamin Black" <b@b3k.us> wrote:
>
> > What you are discovering is that Kafka is a message broker, not a
> database.
> >
> >
> > On Sun, Oct 6, 2013 at 5:34 PM, Ravindranath Akila <
> > ravindranathakila@gmail.com> wrote:
> >
> > > Thanks a lot Neha!
> > >
> > > Actually, using keyed messages(with Simple Consumers) was the approach
> we
> > > took. But it seems we can't map each user to a new partition due to
> > > Zookeeper limitations. Rather, we will have to map a "group" of users
> on
> > > one partition. Then we can't fetch the messages for only one user.
> > >
> > > It seems our data is best put on HBase with a TTL and versioning.
> > >
> > > Thanks!
> > >
> > > R. A.
> > > On 6 Oct 2013 16:00, "Neha Narkhede" <neha.narkhede@gmail.com> wrote:
> > >
> > > > Kafka is designed to have of the order of few thousands of partitions
> > > > roughly less than 10,000. And the main bottleneck is zookeeper. A
> > better
> > > > way to design such a system is to have fewer partitions and use keyed
> > > > messages to distribute the data over a fixed set of partitions.
> > > >
> > > > Thanks,
> > > > Neha
> > > > On Oct 5, 2013 8:19 PM, "Ravindranath Akila" <
> > > ravindranathakila@gmail.com>
> > > > wrote:
> > > >
> > > > > Initially, I thought dynamic topic creation can be used to maintain
> > per
> > > > > user data on Kafka. The I read that partitions can and should be
> used
> > > for
> > > > > this instead.
> > > > >
> > > > > If a partition is to be used to map a user, can there be a million,
> > or
> > > > even
> > > > > billion partitions in a cluster? How does one go about designing
> > such a
> > > > > model.
> > > > >
> > > > > Can the replication tool be used to assign, say partitions 1 -
> 10,000
> > > on
> > > > > replica 1, and 10,001 - 20,000 on replica 2?
> > > > >
> > > > > If not, since there is a ulimit on the file system, should one
> model
> > it
> > > > > based on a replica/topic/partition approach. Say users 1-10,000 go
> on
> > > > topic
> > > > > 10k-1, and has 10,000 partitions, and users 10,0001-20,000 go on
> > topic
> > > > > 10k-2, and has 10,000 partitions.
> > > > >
> > > > > Simply put, how can a million stateful data points be handled? (I
> > > deduced
> > > > > that a userid-partition number mapping can be done via a
> partitioner,
> > > but
> > > > > unless a server can be configured to handle only a given set of
> > > > partitions,
> > > > > with a range based notation, it is almost impossible to handle a
> > large
> > > > > dataset. Is it that Kafka can only handle a limited set of stateful
> > > data
> > > > > right now?)
> > > > >
> > > > >
> > > > >
> > > >
> > >
> >
> http://stackoverflow.com/questions/17205561/data-modeling-with-kafka-topics-and-partitions
> > > > >
> > > > > Btw, why does Kafka have to keep open each partition? Can't a
> > partition
> > > > be
> > > > > opened for read/write when needed only?
> > > > >
> > > > > Thanks in advance!
> > > > >
> > > >
> > >
> >
>

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