@Override
  public List<FieldSchema> acidSortColumns(org.apache.hadoop.hive.ql.metadata.Table table, Operation operation) {
    switch (operation) {
      case DELETE:
        return IcebergTableUtil.isFanoutEnabled(table.getParameters()) ?
            EMPTY_ORDERING : POSITION_DELETE_ORDERING;
      case MERGE:
        return POSITION_DELETE_ORDERING;
      default:
        // For update operations we use the same sort order defined by
        // {@link #createDPContext(HiveConf, org.apache.hadoop.hive.ql.metadata.Table)}
        return EMPTY_ORDERING;
    }
  }
Iceberg's optimistic concurrency control fails to provide means for IOW and Insert operations isolation.
Use `hive.txn.ext.locking.enabled` config to create Hive locks in order to guarantee data consistency.
iceberg/iceberg-handler/src/main/java/org/apache/iceberg/mr/hive/HiveIcebergStorageHandler.java