Consider you want jump to a record in a grid. The grid has huge number of records but we know the id of the record you want jump to. So we can make sure to get the record from server when prefetch the records for the buffered store.
How are you going to do that in a buffered store?
A buffered store MUST only be asked to load pages into its cache. Not individual records.
If you know the page number into which a record which resides only on the server, and has NOT yet been pulled into the cache maps, then you can explicitly request that page.
But If a record is not in the page map, you cannot find it.