I have big and dynamic number of loggers.

According to this https://issues.apache.org/jira/browse/CASSANDRA-16 2GB size limit is no longer an issue in 0.7 (btw mnesia has similar issue ;-) )
I think I can go with svn release at the moment.

Solving this by composite key (logger+timestamp) would require OrderPreservingPartitioner to make efficient range queries, while in first approach in can go with RandomPartitioner (data would be partitioned by logger - simple and effective).

Btw which model provides faster queries ? 
(i need only to get slice (timestamp1 to timestmap2) of data for logger X ) 

On Mon, Jul 5, 2010 at 6:23 PM, Jonathan Ellis <jbellis@gmail.com> wrote:
You don't want to have all the data from a single logger in a single
row b/c of the 2GB size limit.

If you have a small, static number of loggers you could create one CF
per logger and use timestamp as the row key.  Otherwise use a
composite key (logger+timestamp) as the key in a single CF.

2010/7/2 Bartosz Kołodziej <bartosz.kolodziej@gmail.com>:
> I'm new to cassandra, and I want use it to store:
> loggers = { // (super)ColumnFamily ?
>     logger1 : { // row inside super CF ?
>         timestamp1 : {
>             value : 10
>         },
>         timestamp2 : {
>             value : 12
>         }
>         (many many many more)
>     }
>     logger2 : { //logger of diffrent type (in this example it logs 3 values
> instead of 1)
>         timestamp1 : {
>             v : 300,
>             c : 123,
>             s : 12.13
>         },
>         timestamp2 : {
>             v : 300
>             c : 123
>             s : 12.13
>         }
>         (many many many more)
>     }
>     (many many many more)
> }
> the only way i will be accesing this data is:
> - example: fetch slice of data from logger2 ( start = 1278009131 (timestmap)
> , end = 1278109131 )
>      expecting sorted array of data.
> - example: fetch slice of data from (logger2 and logger10 and logger20 and
> logger1234) ( start = 1278009131 (timestmap) , end = 1278109131 )
>      expecting map of sorted arrays of data. [it is basically N queries of
> first type]
> is this right definition of above: <ColumnFamily CompareWith="TimeUUIDType"
> ColumnType="Super"
>     CompareSubcolumnsWith="BytesType" Name="loggers"/> ?
> what's the best way to model this data in cassadra (keeping in mind
> partitioning and other important stuff) ?
>
>
>



--
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of Riptano, the source for professional Cassandra support
http://riptano.com