Read Before Writes on Distributed Counters

Sean Cribbs sean at basho.com
Thu Oct 17 11:45:31 EDT 2013


Since Jeremiah loves it when I'm pedantic, it bears mentioning that the
list of operations are rolled up immediately (not kept around), grouping by
which partition took the increment. So if I increment by 2 and then by 50,
and the increment goes to different replicas, my counter will look like
[{a, 2}, {b, 50}], for a sum of 52.


On Thu, Oct 17, 2013 at 4:21 PM, Jeremiah Peschka <
jeremiah.peschka at gmail.com> wrote:

> When you 'update' a counter, you send in an increment operation. That's
> added to an internal list in Riak. The operations are then zipped up to
> provide the correct counter value on read. The worst that you'll do is add
> a large(ish) number of values to the op list inside Riak.
>
> Siblings will be created, but they will not be visible to the end user who
> is reading from the counter.
>
> Check out this demo of the new counter types from Sean Cribbs:
> https://vimeo.com/43903960
>
> ---
> Jeremiah Peschka - Founder, Brent Ozar Unlimited
> MCITP: SQL Server 2008, MVP
> Cloudera Certified Developer for Apache Hadoop
>
>
> On Thu, Oct 17, 2013 at 9:55 AM, Daniil Churikov <ddosia at gmail.com> wrote:
>
>> Correct me if I wrong, but when you blindly do update without previous
>> read,
>> you create a sibling, which should be resolved on read. In case if you
>> make
>> a lot of increments for counter and rarely reads it will lead to siblings
>> explosion.
>>
>> I am not familiar with new counters datatypes, so I am curious.
>>
>>
>>
>> --
>> View this message in context:
>> http://riak-users.197444.n3.nabble.com/Read-Before-Writes-on-Distributed-Counters-tp4029492p4029498.html
>> Sent from the Riak Users mailing list archive at Nabble.com.
>>
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-- 
Sean Cribbs <sean at basho.com>
Software Engineer
Basho Technologies, Inc.
http://basho.com/
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