A Guide to PostgreSQL Row-Level Security

PostgreSQL: Implementing Row-Level Security (RLS)

PostgreSQL's Row-Level Security (RLS) is a powerful feature that enables fine-grained access control by restricting rows based on user roles, attributes, or other conditions. This feature is useful in multi-tenant applications or when managing sensitive data.

1. Enabling Row-Level Security

To enable RLS on a table, you first need to activate the security policy feature:

ALTER TABLE table_name ENABLE ROW LEVEL SECURITY;

2. Creating Policies

RLS policies define which rows users can interact with. Policies can be applied to SELECT, INSERT, UPDATE, or DELETE operations.

Example: Restrict Access by User

Suppose you have a users table with a column owner_id representing the user who owns the data:

a. Create a policy to allow users to access only their rows:

Code:

CREATE POLICY user_row_access_policy
ON users
USING (owner_id = current_user);

b. To enable this policy, execute:

Code:

ALTER TABLE users FORCE ROW LEVEL SECURITY;

3. Policy Types

4. Testing RLS

To test the applied policies:

a. Switch User:

SET ROLE user_name;

b. Run Queries:

Execute queries to ensure the policy is applied correctly.

5. Disabling RLS

If you want to temporarily disable RLS for debugging or specific use cases:

6. Use Cases for RLS

Additional Notes:

• Performance Impact: Properly define indexes to mitigate performance issues with RLS.
• Audit Policies: Ensure your policies align with security and compliance requirements.

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