Thanks for for reply, David.

I will tell more the detail about the system. My system is used to store the score (point) user earn when they play game.

"Mark" is the score.
User's score changes when user win game, buy or sell anything.

Sorry I make a mistake. My data model is:

Mark{ //Column Family
    gameId:{ //row key
        mark_userId: ""// (column name : value),
        mark2_userId2: ""
    },
    gameId2:{//row key
        mark_userId: ""
    }
}


On Sun, Apr 4, 2010 at 11:44 PM, David Strauss <david@fourkitchens.com> wrote:
On 2010-04-05 02:48, JKnight JKnight wrote:
> I want to design the data storage to store user's mark for a large
> amount of user. When system run, user's mark changes frequently.

What is a "mark"?

> I want to list top 10 user have largest mark.

Do the "marks" increase monotonically? What other properties do they have?

> Could we use Cassandra for store this data?
>
> Ex, here my Cassandra data model design:
> Mark{
>     userId{
>         mark_userId
>     },
> }

I do not understand that notation. What parts are the CF, key/row, and
column?

> When user's mark changes, we remove old mark_userId and add new
> mark_userId.
> Because user's mark change frequently and with large amount  of user, I
> think Cassandra can not satisfy.

On the contrary, Cassandra excels at tracking rapidly changing data and
even shards rows to scale I/O horizontally.

--
David Strauss
  | david@fourkitchens.com
Four Kitchens
  | http://fourkitchens.com
  | +1 512 454 6659 [office]
  | +1 512 870 8453 [direct]




--
Best regards,
JKnight