docs: @Override
      public String getString(int columnIndex) throws SQLException {
          checkColumnBounds(columnIndex);
          try {
              VoltType type = table.getColumnType(columnIndex - 1);
              if (type == VoltType.STRING)
                  return table.getString(columnIndex - 1);
              if (type == VoltType.TIMESTAMP)
                  return getTimestamp(columnIndex).toString();
              if (type == VoltType.VARBINARY)
                  return Encoder.hexEncode(table.getVarbinary(columnIndex-1));
              return table.get(columnIndex - 1, type).toString();
          } catch (Exception x) {
              throw SQLError.get(x);
          }
      }