For a while I have been rumming in my head how a reader could store unlimited number of news without using more ram memory. Bare in mind that this is not my area*. Initially I was thinking of firefox: firefox has a limit of max. opened tabs in (32 bits..) due to memory limit/arquitecture, then how can you "store" more than the limit of max. tabs? If a different profile is created the max number of "stored" tabs will be max x2. Each profile contains it's own index of the tabs and if only one of the profiles is loaded at a time memory usage will remain below the limit.
In a broad sense, the "index" and the tabs of each profile are splitted and if only one is loaded at the time, the other ones "index" and tabs are completely unloaded from memory. What if a modular index was used, each one consisting of a max of xx number of items.
For example let's say that a given database is splitted in 30 small databases each one with the corresponding index that are loaded in demand and managed via a meta-index. Perhaps it would be too complex? or too slow?