(another) Newbie question

[Colin Yates]

Hi,

Assume I have:

SCF: Projects : {
   CF:"project1": { 
         20100101: {cost:10, other columns},
         20100102: {cost:10, other columns},
         .....
         20100120: {cost 10, other columns}
   },
   CF:"project2": { 
         20100105: {cost:12, other columns}
         .....
         20100115: {cost 12, other columns}
  }
}

I know want to display the cost of a project for 2010107-2010109 
where the cost is the average of cost in the snapshot 
(i.e. project1: (3*10/3), project2: (3**12/3)).

I was hoping I could do a get_range_slices specifying 'project*' for the 
columnFamily and a keyRange start: 20100107, end:20100109 but I 
get an error 'InvalidRequestException(why:unconfigured columnfamily project*)'.

This is related to my other post 
(http://permalink.gmane.org/gmane.comp.db.cassandra.user/4003) 
but is the right to do here to have a separate 'snapshots' SCF with 
a key of the snapshot date and the value a CF of projectIds?

Many thanks,

Col