Patent ID: 8700583

Claim:
A computer-implemented method comprising: storing, in a memory, an indexing tier-map that associates key items with one of a plurality of tiers and a serving tier-map that associates the key items with one or more of the plurality of tiers, each tier of the plurality of tiers having a respective associated limit for associations per key item; identifying a first tier assigned to a particular key item of the key items based on the indexing tier-map, the particular key item being assigned to the first tier in the serving tier-map; determining, by one or more processors, whether an amount of associated items approaches the limit for the first tier; updating the indexing tier-map to assign the particular key item to a second tier when the amount of associated items approaches the limit; receiving a new associated item for the particular key item; storing the particular key item with the new associated item in the second tier; adding an assignment of the particular key item to the second tier in the serving tier-map, so that the particular key item is assigned to the first tier and to the second tier in the serving tier-map; receiving a query that relates to the particular key item; and using the serving tier-map to retrieve associated items for the particular key item from the first tier and from the second tier in responding to the query.