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From Mike Gallamore <>
Subject Re: Regarding Cassandra Scalability
Date Fri, 16 Apr 2010 16:17:27 GMT
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 people.
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 
> Dir.
> 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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