Row Access Policies in Snowflake are a powerful data governance feature that enables fine-grained access control at the row level within tables and views. This functionality allows organizations to restrict which rows of data specific users or roles can see, ensuring sensitive information is only a…Row Access Policies in Snowflake are a powerful data governance feature that enables fine-grained access control at the row level within tables and views. This functionality allows organizations to restrict which rows of data specific users or roles can see, ensuring sensitive information is only accessible to authorized personnel.
A Row Access Policy is a schema-level object that contains an expression defining the filtering logic. When applied to a table or view, Snowflake evaluates this expression for each row during query execution, determining whether the current user should see that particular row based on predefined conditions.
The policy uses a combination of the CURRENT_ROLE() or CURRENT_USER() functions along with mapping tables to make access decisions. For example, a healthcare organization might create a policy ensuring doctors only see patient records from their assigned department, while administrators have broader access.
Key characteristics of Row Access Policies include:
1. **Centralized Management**: Policies are defined once and can be applied to multiple tables, simplifying administration and ensuring consistent security enforcement.
2. **Transparent Operation**: End users experience seamless query execution - the filtering happens automatically in the background with no changes required to their SQL statements.
3. **Dynamic Evaluation**: Access decisions are made at query runtime, allowing policies to adapt based on current user context and role assignments.
4. **Stackable Design**: Multiple policies can be applied to the same table when different security requirements exist.
To implement Row Access Policies, users need the appropriate privileges including CREATE ROW ACCESS POLICY at the schema level and APPLY ROW ACCESS POLICY to attach policies to objects. The SECURITYADMIN or ACCOUNTADMIN roles typically manage these permissions.
Row Access Policies complement other Snowflake security features like Column-level Security and Data Masking, providing comprehensive protection for sensitive data while maintaining usability for authorized users across different business contexts.
Row Access Policies in Snowflake
What Are Row Access Policies?
Row Access Policies (RAPs) are a Snowflake feature that enables you to control which rows in a table or view are visible to specific users or roles at query runtime. This is a form of dynamic data masking at the row level, allowing fine-grained access control based on the context of the user executing the query.
Why Are Row Access Policies Important?
Row Access Policies are critical for several reasons:
• Data Security: They protect sensitive information by ensuring users only see data they are authorized to access • Regulatory Compliance: Help organizations meet compliance requirements like GDPR, HIPAA, and SOC 2 by restricting data visibility • Multi-Tenant Applications: Enable secure data separation for SaaS applications where multiple customers share the same database • Simplified Management: Eliminate the need to create multiple views or copies of data for different user groups • Centralized Control: Security logic is defined once and applied consistently across all queries
How Row Access Policies Work
Row Access Policies use a policy-based approach with the following components:
1. Policy Definition: Created using CREATE ROW ACCESS POLICY statement 2. Conditional Expression: A boolean expression that evaluates whether a row should be returned 3. Policy Attachment: The policy is attached to a table or view using ALTER TABLE/VIEW 4. Runtime Evaluation: When a query runs, each row is evaluated against the policy
ALTER TABLE table_name ADD ROW ACCESS POLICY policy_name ON (column_name);
Important Characteristics:
• Only one row access policy can be attached to a table or view at a time • Policies are evaluated for every row returned by a query • The CURRENT_ROLE() and CURRENT_USER() functions are commonly used in policy expressions • Row access policies can reference mapping tables to determine access • Policies are transparent to end users - they simply see fewer rows • The policy owner must have the APPLY ROW ACCESS POLICY privilege
Common Use Cases:
• Restricting sales data by region so representatives only see their territory • Limiting healthcare data access based on patient-provider relationships • Separating customer data in multi-tenant environments • Implementing role-based data visibility for financial reports
Exam Tips: Answering Questions on Row Access Policies
1. Remember the One Policy Rule: Only ONE row access policy can be applied to a table or view at any time. This is a frequently tested concept.
2. Understand the Return Type: Row access policies always return a BOOLEAN value - TRUE means the row is visible, FALSE means it is hidden.
3. Know the Privilege Requirements: The APPLY ROW ACCESS POLICY privilege is required to attach policies to objects.
4. Distinguish from Masking Policies: Row access policies filter rows, while dynamic data masking policies mask column values. Questions may try to confuse these two features.
5. Context Functions: Expect questions involving CURRENT_ROLE(), CURRENT_USER(), and IS_ROLE_IN_SESSION() as these are commonly used in policy definitions.
6. Policy Ownership: The policy is a schema-level object and follows standard Snowflake ownership rules.
7. Performance Consideration: Row access policies add overhead to query execution since each row must be evaluated. Questions may reference this.
8. Mapping Tables: Understand that policies often join to mapping tables to determine which rows a user can see based on their role or attributes.