public MPPDataExchangeServiceImpl getOrCreateMPPDataExchangeServiceImpl() {
    if (mppDataExchangeService == null) {
      mppDataExchangeService = new MPPDataExchangeServiceImpl();
    }
    return mppDataExchangeService;
  }
Each FI has only one ShuffleSinkHandle.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/execution/exchange/MPPDataExchangeManager.java