# Iceberg表服务
Aura提供一系列表服务，用户可以根据需要使用，例如清理旧快照，整理元数据、数据文件等，以提高存储、查询的效率。具体语法可参考[Iceberg表服务函数](https://support.huaweicloud.com/sqlref-aura-aidatalake/aidatalake_061_0198.html)。
示例：
- 清理旧快照
  ```
  select * from iceberg_expire_snapshots('iceberg_test','2025-05-15 14:12:00+08');
  deleted_data_files_count | deleted_position_delete_files_count | deleted_equality_delete_files_count | deleted_manifest_files_count | deleted_manifest_lists_count | deleted_statistics_files_count
  ----------------------------+---------------------------------------+----------------------------------------+--------------------------------+--------------------------------+--------------------------------
  0                                       | 0                                                        | 0                                                         | 0                                             | 3                                              | 0
  (1 row)
  ```
  
- 重写元数据文件
  ```
  SELECT * from iceberg_rewrite_manifests('test1');
  rewritten_manifests_count | added_manifests_count
  ---------------------------+-----------------------
  2                                     | 1
  (1 row)
  ```
  
- 清除孤立文件
  ```
  SELECT * from iceberg_remove_orphanfiles('iceberg_test');
  orphan_file_location
  -------------------------------------------------------------
  obs://xxxx/test.txt
  obs://xxxx/test2.txt
  (2 rows)
  ```
  
- 重写数据文件
  ```
  OPTIMIZE reason_t2 REWRITE DATA WITH OPTIONS ('rewrite-all' = 'true') WHERE TABLE_SC = 'Hainan';
  INSERT 2
  ```