a system and method for creating and managing a space - efficient , durable key - value map is disclosed . a key management engine initializes a key - value map by associating a plurality of keys with a first slot of the slots in the key - value map . a first key - value pair is then assigned to the first slot of the key - value map . the key management engine subsequently receives an indication that the first key is to be invalidated ; and responsively reuses the first slot of the key - value map by assigning a second key - value pair to the first slot . the first key is then recycled in response to the first key becoming valid . the first and second key - value pairs include respective first and second values and respective first and second keys of the plurality of keys associated with the first slot . the first key becomes valid when it is no longer referenced by a data buffer .