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/)。

# 动态数据掩蔽端到端示例
<a name="ddm-example"></a>

下面是一个端到端的示例，显示了如何创建屏蔽策略并将其附加到列。这些策略让用户可以访问列并查看不同的值，具体取决于与其角色相关的策略的混淆程度。您必须是超级用户或具有 [https://docs.aws.amazon.com/redshift/latest/dg/r_roles-default.html](https://docs.aws.amazon.com/redshift/latest/dg/r_roles-default.html) 角色才能运行此示例。

## 创建屏蔽策略
<a name="ddm-example-create"></a>

首先，创建一个表并填入信用卡值。

```
--create the table         
CREATE TABLE credit_cards (
  customer_id INT,
  credit_card TEXT
);

--populate the table with sample values
INSERT INTO credit_cards
VALUES
  (100, '4532993817514842'),
  (100, '4716002041425888'),
  (102, '5243112427642649'),
  (102, '6011720771834675'),
  (102, '6011378662059710'),
  (103, '373611968625635')
;

--run GRANT to grant permission to use the SELECT statement on the table
GRANT SELECT ON credit_cards TO PUBLIC;

--create two users
CREATE USER regular_user WITH PASSWORD '1234Test!';

CREATE USER analytics_user WITH PASSWORD '1234Test!';

--create the analytics_role role and grant it to analytics_user
--regular_user does not have a role
CREATE ROLE analytics_role;

GRANT ROLE analytics_role TO analytics_user;
```

接下来，创建应用于分析角色的屏蔽策略。

```
--create a masking policy that fully masks the credit card number
CREATE MASKING POLICY mask_credit_card_full
WITH (credit_card VARCHAR(256))
USING ('000000XXXX0000'::TEXT);

--create a user-defined function that partially obfuscates credit card data
CREATE FUNCTION REDACT_CREDIT_CARD (credit_card TEXT)
RETURNS TEXT IMMUTABLE
AS $$
    import re
    regexp = re.compile("^([0-9]{6})[0-9]{5,6}([0-9]{4})")
 
    match = regexp.search(credit_card)
    if match != None:
        first = match.group(1)
        last = match.group(2)
    else:
        first = "000000"
        last = "0000"
    
    return "{}XXXXX{}".format(first, last)
$$ LANGUAGE plpythonu;

--create a masking policy that applies the REDACT_CREDIT_CARD function
CREATE MASKING POLICY mask_credit_card_partial
WITH (credit_card VARCHAR(256))
USING (REDACT_CREDIT_CARD(credit_card));

--confirm the masking policies using the associated system views
SELECT * FROM svv_masking_policy;

SELECT * FROM svv_attached_masking_policy;
```

## 附加屏蔽政策
<a name="ddm-example-attach"></a>

将屏蔽政策附加到信用卡表中。

```
--attach mask_credit_card_full to the credit card table as the default policy
--all users will see this masking policy unless a higher priority masking policy is attached to them or their role
ATTACH MASKING POLICY mask_credit_card_full
ON credit_cards(credit_card)
TO PUBLIC;

--attach mask_credit_card_partial to the analytics role
--users with the analytics role can see partial credit card information
ATTACH MASKING POLICY mask_credit_card_partial
ON credit_cards(credit_card)
TO ROLE analytics_role
PRIORITY 10;

--confirm the masking policies are applied to the table and role in the associated system view
SELECT * FROM svv_attached_masking_policy;

--confirm the full masking policy is in place for normal users by selecting from the credit card table as regular_user
SET SESSION AUTHORIZATION regular_user;

SELECT * FROM credit_cards;

--confirm the partial masking policy is in place for users with the analytics role by selecting from the credit card table as analytics_user
SET SESSION AUTHORIZATION analytics_user;

SELECT * FROM credit_cards;
```

## 修改掩蔽政策
<a name="ddm-example-alter"></a>

以下部分介绍了如何修改动态数据掩蔽政策。

```
--reset session authorization to the default
RESET SESSION AUTHORIZATION;

--alter the mask_credit_card_full policy
ALTER MASKING POLICY mask_credit_card_full
USING ('00000000000000'::TEXT);	
	
--confirm the full masking policy is in place after altering the policy, and that results are altered from '000000XXXX0000' to '00000000000000'
SELECT * FROM credit_cards;
```

## 分离和删除屏蔽策略
<a name="ddm-example-detach"></a>

以下部分显示如何通过从表中删除所有动态数据掩蔽策略来分离和删除屏蔽策略。

```
--reset session authorization to the default
RESET SESSION AUTHORIZATION;

--detach both masking policies from the credit_cards table
DETACH MASKING POLICY mask_credit_card_full 
ON credit_cards(credit_card) 
FROM PUBLIC;

DETACH MASKING POLICY mask_credit_card_partial 
ON credit_cards(credit_card) 
FROM ROLE analytics_role;

--drop both masking policies
DROP MASKING POLICY mask_credit_card_full;

DROP MASKING POLICY mask_credit_card_partial;
```