docs: protected String[] getPrimaryKeysList(String schema, String tableName)
  			throws DatabaseException {
  		try {
  			DatabaseMetaData dmd = connection.getMetaData();
  			ResultSet rs = dmd.getPrimaryKeys(dbName, schema, tableName);
  			List<String> columnList = new ArrayList<String>();
  			try {
  				while (rs.next()) {
  					columnList.add(rs.getString("COLUMN_NAME"));
  				}
  			} finally {
  				rs.close();
  			}
  			String[] primaryKeys = columnList.toArray(new String[columnList
  			                                                     .size()]);
  			return primaryKeys;
  		} catch (SQLException e) {
  			e.printStackTrace();
  			throw new DatabaseException();
  		}
  	}