从补丁 198 开始，Amazon Redshift 将不再支持创建新的 Python UDF。现有的 Python UDF 将继续正常运行至 2026 年 6 月 30 日。有关更多信息，请参阅[博客文章](https://aws.amazon.com/blogs/big-data/amazon-redshift-python-user-defined-functions-will-reach-end-of-support-after-june-30-2026/)。

# 动态数据掩蔽系统视图
<a name="r_ddm-svv"></a>

超级用户、具有 `sys:operator` 角色的用户和具有 ACCESS SYSTEM TABLE 权限的用户可以访问以下与 DDM 相关的系统视图。
+  [SVV\_MASKING\_POLICY](r_SVV_MASKING_POLICY.md) 

   使用 SVV\_MASKING\_POLICY 可查看在集群或工作组上创建的所有屏蔽策略。
+  [SVV\_ATTACHED\_MASKING\_POLICY](r_SVV_ATTACHED_MASKING_POLICY.md) 

  使用 SVV\_ATTACHED\_MASKING\_POLICY 可查看已在当前连接的数据库上附加了策略的所有关系和角色或用户。
+  [SYS\_APPLIED\_MASKING\_POLICY\_LOG](SYS_APPLIED_MASKING_POLICY_LOG.md) 

  使用 SYS\_APPLIED\_MASKING\_POLICY\_LOG 可跟踪屏蔽策略在引用受 DDM 保护关系的查询上的应用情况。

下面是使用系统视图可以找到的一些信息示例。

```
--Select all policies associated with specific users, as opposed to roles
SELECT policy_name,
       schema_name,
       table_name,
       grantee
FROM svv_attached_masking_policy
WHERE grantee_type = 'user';     

--Select all policies attached to a specific user
SELECT policy_name,
       schema_name,
       table_name,
       grantee
FROM svv_attached_masking_policy
WHERE grantee = '{{target_grantee_name}}'            
            
--Select all policies attached to a given table
SELECT policy_name,
       schema_name,
       table_name,
       grantee
FROM svv_attached_masking_policy
WHERE table_name = '{{target_table_name}}'
      AND schema_name = '{{target_schema_name}}';            
            
--Select the highest priority policy attachment for a given role
SELECT samp.policy_name,
       samp.priority,
       samp.grantee,
       smp.policy_expression
FROM svv_masking_policy AS smp
JOIN svv_attached_masking_policy AS samp
    ON samp.policy_name = smp.policy_name
WHERE
    samp.grantee_type = 'role' AND
    samp.policy_name = mask_get_policy_for_role_on_column(
        '{{target_schema_name}}', 
        '{{target_table_name}}', 
        '{{target_column_name}}', 
        '{{target_role_name}}')
ORDER BY samp.priority desc
LIMIT 1;         

--See which policy a specific user will see on a specific column in a given relation
SELECT samp.policy_name,
       samp.priority,
       samp.grantee,
       smp.policy_expression
FROM svv_masking_policy AS smp
JOIN svv_attached_masking_policy AS samp
    ON samp.policy_name = smp.policy_name
WHERE
    samp.grantee_type = 'role' AND
    samp.policy_name = mask_get_policy_for_user_on_column(
        '{{target_schema_name}}',
        '{{target_table_name}}',
        '{{target_column_name}}',
        '{{target_user_name}}')
ORDER BY samp.priority desc; 
         
 --Select all policies attached to a given relation.
SELECT policy_name,
schema_name,
relation_name,
database_name
FROM sys_applied_masking_policy_log
WHERE relation_name = 'relation_name'
AND schema_name = 'schema_name';
```