}
public NodePool openExistingNodePool() {
nodePoolMapFactory = new BdbMapFactory(handler, DB_NAME_NODEPOOL + graphNumber);
stringPoolMapFactory = new BdbMapFactory(handler, DB_NAME_STRINGPOOL + graphNumber);
StringNodeMapper mapper = new StringNodeMapperFactoryImpl().createMapper();
final Map<Long, String> blankNodePool = nodePoolMapFactory.openExistingMap(Long.class, String.class, "bnp");
final Map<Long, String> uriNodePool = nodePoolMapFactory.openExistingMap(Long.class, String.class, "npm");
final Map<Long, String> literalNodePool = nodePoolMapFactory.openExistingMap(Long.class, String.class, "lnp");
final Map<String, Long> stringPool = stringPoolMapFactory.openExistingMap(String.class, Long.class, "sp");
final NodeTypePool nodeTypePool = new NodeTypePoolImpl(mapper, blankNodePool, uriNodePool, literalNodePool);