public final int topologicalCompareTo(@Nonnull ProgressIndex progressIndex) {
    return getTotalOrderSumTuple().compareTo(progressIndex.getTotalOrderSumTuple());
  }
Get the sum of the tuples of each total order relation of the {@link ProgressIndex}, which is
used for topological sorting of the {@link ProgressIndex}.

@return The sum of the tuples corresponding to all the total order relations contained in the
    progress index.
iotdb-core/node-commons/src/main/java/org/apache/iotdb/commons/consensus/index/ProgressIndex.java