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From aaron morton <aa...@thelastpickle.com>
Subject Re: Store a timeline with uniques properties
Date Fri, 31 Aug 2012 04:05:14 GMT
Consider trying…

UserTimeline CF

row_key: <user_id>
column_names: <timestamp, other_user_id, action>
column_values: action details

To get the changes between two times specify the start and end timestamps and do not include
the other components of the column name. 

e.g. from <1234, NULL, NULL> to <6789, NULL, NULL>

Cheers

-----------------
Aaron Morton
Freelance Developer
@aaronmorton
http://www.thelastpickle.com

On 30/08/2012, at 11:32 PM, Morgan Segalis <msegalis@gmail.com> wrote:

> Sorry for the scheme that has not keep the right tabulation for some people...
> Here's a space-version instead of a tabulation.
> 
> user1 row :            |               lte                    |              lte -1 
              |               lte -2                |              lte -3               |
              lte -4               |
>          values :        | user2-name-change | user3-pic-change       | user4-status-change
| user2-pic-change     | user2-status-change |
> 
> If for example, user2 changes it's picture, the row should look like that : 
> 
> user1 row :                    |                lte                   |             
 lte -1               |               lte -2               |                lte -3       
      |              lte -4                |
>                values :          |   user2-pic-change    | user2-name-change | user3-pic-change
      | user4-status-change | user2-status-change |
> 
> Le 30 août 2012 à 13:22, Morgan Segalis a écrit :
> 
>> Hi everyone,
>> 
>> I'm trying to use cassandra in order to store a "timeline", but with values that
must be unique (replaced). (So not really a timeline, but didn't find a better word for it)
>> 
>> Let's me give you an example :
>> 
>> - An user have a list of friends
>> - Friends can change their nickname, status, profile picture, etc...
>> 
>> at the beginning the CF will look like that for user1: 
>> 
>> lte = latest-timestamp-entry, which is the timestamp of the entry (-1 -2 -3 means
that the timestamp are older)
>> 
>> user1 row :			|		lte			|		lte -1		|		lte -2		| 		lte -3		|		lte -4		|
>> 		values :		| user2-name-change | user3-pic-change	| user4-status-change | user2-pic-change
| user2-status-change |
>> 
>> If for example, user2 changes it's picture, the row should look like that : 
>> 
>> user1 row :			|		lte			|		lte -1		|		lte -2		| 		lte -3		|		lte -4		 |
>> 		values :		|   user2-pic-change	| user2-name-change | user3-pic-change	| user4-status-change
| user2-status-change |
>> 
>> notice that user2-pic-change in the first representation (lte -3) has "moved" to
the (lte) on the second representation.
>> 
>> That way when user1 connects again, It can retrieve only informations that occurred
between the last time he connected.
>> 
>> e.g. : if the user1's last connexion date it between "lte -2" and "lte -3", then
he will only be notified that :
>> 
>> - user2 has changed his picture
>> - user2 has changed his name
>> - user3 has changed his picture
>> 
>> I would not keep the old data since the "timeline" is saved locally on the client,
and not on the server.
>> I really would like not to search for each column in order to find the "user2-pic-change",
that can be long especially if the user has many friends.
>> 
>> Is there a simple way to do that with cassandra, or I am bound to create another
CF, with column title holding the action e.g. "user2-pic-change" and for value the timestamp
when it appears ?
>> 
>> Thanks,
>> 
>> Morgan.
>> 
> 


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