cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Jake Luciani <jak...@gmail.com>
Subject Re: Facebook messaging and choice of HBase over Cassandra - what can we learn?
Date Sun, 21 Nov 2010 21:58:24 GMT
+1 Ed 

 

On Nov 21, 2010, at 12:13 PM, Edward Capriolo <edlinuxguru@gmail.com> wrote:

> On Sun, Nov 21, 2010 at 12:10 PM, André Fiedler
> <fiedler.andre@googlemail.com> wrote:
>> Facebook Messaging – HBase Comes of Age
>> 
>> http://facility9.com/2010/11/18/facebook-messaging-hbase-comes-of-age
>> 
>> 2010/11/21 David Boxenhorn <david@lookin2.com>
>>> 
>>> Eventual consistency is not good enough for instant messaging.
>>> 
>>> On Sun, Nov 21, 2010 at 6:32 PM, Simon Reavely <simon.reavely@gmail.com>
>>> wrote:
>>>> 
>>>> (Posting this to both user + dev lists)
>>>> 
>>>> I was reviewing the blog post on the facebook engineering blog from nov
>>>> 15th
>>>> http://www.facebook.com/note.php?note_id=454991608919#
>>>> <http://www.facebook.com/note.php?note_id=454991608919#>
>>>> The Underlying Technology of Messages
>>>> by Kannan Muthukkaruppan <http://www.facebook.com/Kannan>
>>>> 
>>>> 
>>>> 
>>>> As a cassandra user I think the key sentence for this community is:
>>>> "We found Cassandra's eventual consistency model to be a difficult
>>>> pattern
>>>> to reconcile for our new Messages infrastructure."
>>>> 
>>>> I think it would be useful to find out more about this statement from
>>>> Kannan
>>>> and the facebook team. Does anyone have any contacts in the Facebook
>>>> team?
>>>> 
>>>> My goal here is to understand usage patterns and whether or not the
>>>> Cassandra community can learn from this decision; maybe even understand
>>>> whether the Cassandra roadmap should be influenced by this decision to
>>>> address a target user base. Of course we might also conclude that its
>>>> just
>>>> "not a Cassandra use-case"!
>>>> 
>>>> Cheers,
>>>> Simon
>>>> --
>>>> Simon Reavely
>>>> simon.reavely@gmail.com
>>> 
>> 
>> 
> 
> 
> 
> On Sun, Nov 21, 2010 at 11:40 AM, David Boxenhorn <david@lookin2.com> wrote:
>> Eventual consistency is not good enough for instant messaging.
>> 
>> On Sun, Nov 21, 2010 at 6:32 PM, Simon Reavely <simon.reavely@gmail.com>
>> wrote:
>>> 
>>> (Posting this to both user + dev lists)
>>> 
>>> I was reviewing the blog post on the facebook engineering blog from nov
>>> 15th
>>> http://www.facebook.com/note.php?note_id=454991608919#
>>> <http://www.facebook.com/note.php?note_id=454991608919#>
>>> The Underlying Technology of Messages
>>> by Kannan Muthukkaruppan <http://www.facebook.com/Kannan>
>>> 
>>> 
>>> 
>>> As a cassandra user I think the key sentence for this community is:
>>> "We found Cassandra's eventual consistency model to be a difficult pattern
>>> to reconcile for our new Messages infrastructure."
>>> 
>>> I think it would be useful to find out more about this statement from
>>> Kannan
>>> and the facebook team. Does anyone have any contacts in the Facebook team?
>>> 
>>> My goal here is to understand usage patterns and whether or not the
>>> Cassandra community can learn from this decision; maybe even understand
>>> whether the Cassandra roadmap should be influenced by this decision to
>>> address a target user base. Of course we might also conclude that its just
>>> "not a Cassandra use-case"!
>>> 
>>> Cheers,
>>> Simon
>>> --
>>> Simon Reavely
>>> simon.reavely@gmail.com
>> 
>> 
> 
> Jonathan Ellis pointed out a term that I like using better "Tunable
> consistency" . It seems that "eventual consistency" confuses everyone,
> that or it is an easy target of an anti Cassandra public relation
> campaign. If you want consistency use:
> 
> WRITE.ALL + READ.ONE (hinted handoff off)
> WRITE.QUORUM + READ.QUORUM
> WRITE.ONE + READ.ALL
> 
> Also I believe saying HBASE is consistent is not true. This can happen:
> Write to region server. -> Region Server acknowledges client-> write
> to WAL -> region server fails = write lost
> 
> I wonder how facebook will reconcile that. :)
> 
> Not trying to be nitpicky, at hadoop world in NYC I got to sit with
> lots of the hbase guys and we all had a great time talking about the
> mutual issues and happiness both of our communities share.
> 
> We can not speak for Facebook, but likely chose HBase because they
> have several of hadoop core developers and have a large hadoop
> deployment. I would say the decision was probably based on several
> things. Current Cassandra release does not do on line schema updates.
> I am sure facebook does not want to restart 10,000 cassandra servers
> for a schema change. Current release does not have memtable tuning per
> column family. The upcoming Cassandra release has support for both of
> these things and many many more awesome things.
> 
> Facebook is on the high end of how much data they have to manage, and
> how many servers they have. Most people do not share that use case. We
> can learn that facebook chose software that was good for them based on
> their use case and the experience they have in house. Something
> everyone should do.

Mime
View raw message