code: public MetaDataEntity getMetadata(int iid) throws Exception {
  		if (iid < 0 || iid > loadCounter) {
  			System.out.println("Internal id " + iid + " is out of range!");
  			return null;
  		}
  		PrimaryIndex<Integer, MetaDataEntity> primaryIndex = iidToMetadataDB.getPrimaryIndex(Integer.class,
  				MetaDataEntity.class);
  		return primaryIndex.get(null, iid, null);
  	}
docs: Returns a {@link MetaDataEntity} object with the metadata of the vector with the given internal id or
  null if the internal id does not exist. Accesses the BDB store!
  
  @param iid
  The internal id of the vector
  @return The metadata mapped to the given internal id or null if the internal id does not exist