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From Peter Chang <pete...@gmail.com>
Subject Re: Model Question
Date Wed, 24 Mar 2010 22:57:14 GMT
If there's not much overhead, I recommend client side as well.

Otherwise, you can only sort on column. Therefore, you could create some
sort of inverted index based on the message count.

User 1 sent 50 messages.
User 2 sent 10 messages.
User 3 sent 25 messages.

Then store a separate index that looks like:
  ->  50-User-1-Key
  ->  25-User-2-Key
  ->  10-User-2-Key

You'd also have to 0-pad your count so that numbers are correctly compared
(12 is less than 110) since you'll have to use some lexical-based sorting.



On Wed, Mar 24, 2010 at 1:36 PM, Erez Efrati <erezef@gmail.com> wrote:

> Hi,
>
> I can't figure out how to use model the following using column family and
> the way the columns are sorted (by their name).
>
> Lets say I have a list of users and for each user I wish to display a list
> of all the friends he has ordered by the number of messages they sent him so
> far (desc from most to least).
>
> I can't see how this is going to work since the columns sorting is always
> by the name of the column and not its value. I thought of having a row for
> each user and the columns will be the friends that email him. But the column
> name needs to be the number of messages to be sorted and the value will be
> the friend's user ID. But then, when a friend is sending a message to
> another user how do I increment his count of message he sent so far to that
> user?
>
> How can I model this with Cassandra? Is it possible?
>
> Thanks in advance,
>
> Erez Efrati
>

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