code: public byte[] getPQCodeByte(String id) throws Exception {
  		int iid = getInternalId(id);
  		if (iid == -1) {
  			throw new Exception("Id does not exist!");
  		}
  		if (numProductCentroids > 256) {
  			throw new Exception("Call the short variant of the method!");
  		}
  
  		DatabaseEntry key = new DatabaseEntry();
  		IntegerBinding.intToEntry(iid, key);
  		DatabaseEntry data = new DatabaseEntry();
  		if ((iidToIvfpqDB.get(null, key, data, null) == OperationStatus.SUCCESS)) {
  			TupleInput input = TupleBinding.entryToInput(data);
  			input.readInt(); // skip the list id
  			byte[] code = new byte[numSubVectors];
  			for (int i = 0; i < numSubVectors; i++) {
  				code[i] = input.readByte();
  			}
  			return code;
  		} else {
  			throw new Exception("Id does not exist!");
  		}
  	}
docs: Returns the pq code of the image with the given id.
  
  @param id
  @return
  @throws Exception