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From S Ahmed <>
Subject Re: understanding partitions based on wiki example of profile visits
Date Mon, 26 Nov 2012 17:19:31 GMT
>Yes, your description is correct. A particular member's data would all be
>in one partition.
When you say in one partition, that also means on the same server?  Or a
partition can span a brocker node?

At the file level, I'm guessing it has its own physical file then? (or set
of files as it grows with the file number suffix).

So at linkedIn, is this how you present a users dashboard inbox (your
friend has a new job, they updated their profile, someone recommended them,
etc.)   I guess you can further sort at the application level then, and
cache to a different store?

On Mon, Nov 26, 2012 at 11:53 AM, Jay Kreps <> wrote:

> Yes, your description is correct. A particular member's data would all be
> in one partition.
> Broker partitions are just the unit of parallelism--think of each partition
> as a totally ordered log you can append to and read from. The consumption
> of one of these partition logs is single threaded.
> The guarantee is that all messages are added to a partition in the order
> they arrive. From the point of view of a single producer client this will
> also be the order in which they are sent. These messages are then delivered
> in this order to a consumer thread.
> Hope that helps.
> -Jay
> On Sun, Nov 25, 2012 at 7:54 PM, S Ahmed <> wrote:
> > The wiki states "Consider an application that would like to maintain an
> > aggregation of the number of profile visitors for each member. It would
> > like to send all profile visit events for a member to a particular
> > partition and, hence, have all updates for a member to appear in the same
> > stream for the same consumer thread." (
> >
> >
> > So say I have 5 broker servers, now my producer will send a message for a
> > particular profile page visit, with the default algorithm using
> > hash(member_id)%num_partitions
> > to figur out which broker server to send it it.
> >
> > So a particular members pageview messages will all go to a single server
> > then, is this the case?  And therefore all the messages for a given user
> > will be in the correct order also right?
> >
> > So a consumer group that subscribes to the 'profile-page-view' topic will
> > consume page view related messages, is it possible to subscribe to a
> > particular broker partition also?
> >
> > Are broker partitions meant for cases when you want all messages to be
> > saved on the same node?
> >

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