@Override
 protected void addStatementInternal(Resource subj, URI pred, Value obj, Resource... contexts)
     throws SailException {
   try {
     if (contexts.length == 0) {
       triples.add(vf.createStatement(subj, pred, obj));
     } else {
       for (Resource ctx : contexts) {
         triples.add(vf.createStatement(subj, pred, obj, ctx));
       }
     }
   } catch (SQLException e) {
     throw new RdbmsException(e);
   } catch (InterruptedException e) {
     throw new RdbmsException(e);
   }
 }