@Override
  public ContinuousEnumerationResult planSplits(
      MixedFormatEnumeratorOffset ignored, List<Expression> filters) {
    // todo support mor the table from the specific offset in the future
    if (table == null) {
      table = loadMixedTable(loader).asKeyedTable();
    }
    table.refresh();
    return discoverInitialSplits(filters);
  }
Used for MergeOnRead, only for the bounded reading and return append stream.
amoro-format-mixed/amoro-mixed-flink/amoro-mixed-flink-common/src/main/java/org/apache/amoro/flink/read/hybrid/enumerator/MergeOnReadPlannerImpl.java