Add to Cached data?

Is it possible to add to cached data for a user?

 

User has a list of saved  "ads" for people selling / buying stuff classifieds type set up...then they bookmark a new "ad" can you add that data to the current cached data? Or you have to delete all and query all data again and save it?

 

They can click "my ads" to view all the ones they saved but rather than running a query each time figure you could keep adding to the cache after each save rather than having to query ads they have saved over and over.

 

Thanks,

 

Dave