Systems and methods for managing a tier-map of key items are disclosed. A system may include tiers having at least one tier limit, an indexing tier-map that maps key items to one of the tiers and a serving tier-map that maps key items to one or more of the tiers. The system may also include a memory storing instructions that cause a processor to perform operations. The operations may include using the indexing tier-map to determine that a particular key item is mapped to a first tier, determining that an amount of associated items for the particular key item approaches the tier limit, and updating the indexing tier-map to map the particular key item to map to a second tier. The operations may further include identifying a new associated item for the particular key item and storing the new associated item with the particular key item in the second tier.