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From David Boxenhorn <>
Subject Re: Facebook messaging and choice of HBase over Cassandra - what can we learn?
Date Mon, 22 Nov 2010 08:57:07 GMT
It's true that Cassandra has "tunable consistency", but if eventual
consistency is not sufficient for most of your use cases, Cassandra becomes
much less attractive. Am I wrong?

On Sun, Nov 21, 2010 at 7:56 PM, Eric Evans <> wrote:

> On Sun, 2010-11-21 at 11:32 -0500, Simon Reavely wrote:
> > 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."
> In my experience, "we needed strong consistency", in conversations like
> these amounts to hand waving.  It's the fastest way to shut down that
> part of the discussion without having said anything at all.
> > 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?
> Good luck.  Facebook is notoriously tight-lipped about such things.
> > 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"!
> Understanding is a laudable goal, just try to avoid drawing conclusions
> (and call out others who are).
> <rant>
> This is usually the point where a frenzy kicks in and folks assume that
> the Smart Guys at Facebook know something they don't, something that
> would invalidate their decision if they'd only known.
> I seriously doubt they've uncovered some Truth that would fundamentally
> alter the reasoning behind *my* decision to use Cassandra, and so I plan
> to continue as I always have.  Following relevant research and
> development, collecting experience (my own and others), and applying it
> to the problems I face.
> </rant>
> --
> Eric Evans

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