@Override
  public void open() {
    recordState.open();
    recordState.addGauge(UNIQUE_CACHE_SIZE, () -> recordState.guavaCache.size());
  }
Use a unique index to lookup. Working for the situation where the join keys include the
mixed-format table's primary keys.
amoro-format-mixed/amoro-mixed-flink/amoro-mixed-flink-common/src/main/java/org/apache/amoro/flink/lookup/UniqueIndexTable.java