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From Peter Chang <>
Subject Re: Regarding Cassandra Scalability
Date Fri, 16 Apr 2010 16:41:16 GMT
FB also does pics and movies so 1MB is way off depending on where they
manage such binary data. I do agree that 1MB of text alone is a lot of text
which is more relevant in the case of Twitter. The only large thing you
leave out is denormalization. Every tweet you write is likely denormalized
across your followers to allow for quick read access.

Sent from my iPhone

On Apr 16, 2010, at 10:17 AM, Mike Gallamore <> wrote:

On 04/16/2010 01:38 AM, dir dir wrote:

I hear and using cassandra database. In my opinion
Facebook and
tweeter have hundreds TB data.  because their user reach hundreds million

I think you might be forgetting just how tiny tweets are. The last numbers I
heard tweeter gets 55,000,000 messages a day. They've been around for
roughly 4 years. Even assuming they always had that number of messages
(which isn't the case) that still would only be roughly 11TB of data if
everyone sent the maximum tweet length. Sure add a bit to each message for a
time stamp and the user that posted it but still I'd be surprised if every
tweet including meta data was much more than 20TB.

Similarly with Facebook. I think it is the friend list search that they
really did it with. Regardless how much text is on your Facebook page? Maybe
1MB if you are a very very active user. The images I wouldn't think they
would load directly into Cassandra but I could be wrong, I would suspect
that they would pull an old database trick and have filesystem store the
images and the "database" just stores the path to it.

There could be a lot of other data floating around some of which might be in
Cassandra but I don't know. Just the core data that the sites have mentioned
that they use Cassandra for I think is probably in the very low 10's of TB.

Lastly sites like Facebook and Tweeter count hundreds of millions of users
but a lot of them are people that sign in, send a few tweets or connect to a
few friends and then don't use the site again. When the company needs to
make themselves look valuable they count every single person that ever
logged in, even if they only did it once or haven't used the site for years.
They want to sell large numbers because that is what advertisers/potential
acquirers to base the price on those large numbers.


On Fri, Apr 16, 2010 at 1:28 PM, Linton N <>wrote:

> hi ,
>          I am working for the past 1 year with hadoop, but quite new to
> cassandra, I would like to get clarified few things regarding the
> scalability of Cassandra. Can it scall up to TB of data ?
> Please provide me some links regarding this..
> --
> --
> With Love
>  Lin N

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