The delta process allows you to add specific data for a query to the cache. This means that you no longer have to read all data for the query from the database when the data basis changes. However, a complete rebuild of the cache is always necessary if metadata, master data , hierarchies, exchange rates and so on change. But a complete rebuild of the cache object also has to be performed for InfoProviders that are not suitable for the delta process when changes take place. InfoProviders are delta process enabled when a time stamp, a sequential number or - as with InfoCubes - the request shows which entries have been added.
see also Delta Cache