reading the updated values

[subhankar biswas]

hi,
   i m trying to use cassandra as main data-store and elasticsearch for
realtime quries. my question is how do i get the updated data in cassandra
for last 1 hour or so to be indexed in elasticsearch.
   once i get the updated data from cassandra i can index that to ES.
   is there any specific data model i have to follow to get the recent
updates of any CF.

   thanks subhankar