@Override
  public KeySelector<RowData, ShuffleKey> generateKeySelector() {
    return new PrimaryKeySelector();
  }
Shuffle RowData with same key to same subtask, to make sure cdc data with same key in order.
amoro-format-mixed/amoro-mixed-flink/amoro-mixed-flink-common/src/main/java/org/apache/amoro/flink/shuffle/ReadShuffleRulePolicy.java