code: public static String getSignatureForTable(String name, SortedMap<Integer, VoltType> schema) {
          StringBuilder sb = new StringBuilder();
          sb.append(name).append(SIGNATURE_TABLE_NAME_SEPARATOR);
          for (VoltType t : schema.values()) {
              sb.append(t.getSignatureChar());
          }
          return sb.toString();
      }
docs: Get a string signature for the table represented by the args
  @param name The name of the table
  @param schema A sorted map of the columns in the table, keyed by column index
  @return The table signature string.