How to store logical objects inside physical Aerospike objects to reduce key space size

storeDeviceMetaDataUsingBlocking.java

    public static final int BIT_MASK_SIZE = 25;
    public static final BigInteger BIT_MASK = (new BigInteger("2")).pow(BIT_MASK_SIZE).subtract(new BigInteger("1"));
    public static final String METADATA_BIN_NAME = "deviceMetaData";
    public static final AerospikeClient aeroClient = new AerospikeClient(hostName,aerospikeServicePort);

    /**
     * Store device meta data in Aerospike using 'blocking' technique
     * @param deviceIDasUUID - device id
     * @param deviceMetaData - metadat
     */
    public void storeDeviceMetaData(UUID deviceIDasUUID ,Map<String,Object> deviceMetaData){
        // Turn UUID into a BigInteger to help with bit masking
        BigInteger deviceID = new BigInteger(deviceIDasUUID.toString().replace("-",""),32);
        // Do bit masking
        BigInteger physicalKey = deviceID.and(BIT_MASK);
        // Construct Aerospike key using key built using bit masking
        Key aerospikeKey= new Key(deviceDataNamespace,deviceDataSetName,physicalKey.toString());

        // Store using Map API - stores device metadata in an Aerospike object using the bit masked key
        // but within that object inserts to a map using the device id as a key
        aeroClient.operate(new WritePolicy(),aerospikeKey,
                MapOperation.put(new MapPolicy(),METADATA_BIN_NAME,Value.get(deviceIDasUUID.toString()),   Value.get(deviceMetaData)));
    }