private Slice getSlice(int startPartitionIndex, int endPartitionIndex) {
    return new Slice(
        startPartitionIndex,
        endPartitionIndex,
        currentTsBlock.getValueColumns(),
        requiredChannels,
        passThroughChannels,
        inputDataTypes);
  }
Find next row index whose partition values are different from the current partition values. If
all rows have the same partition values, return the position count of the current TsBlock.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/execution/operator/process/function/PartitionRecognizer.java