Microsoft Presidio Row-Level Security

The query returned zero rows, but you know the data is there. The problem isn’t the SQL—it’s the security layer you can’t see. Microsoft Presidio combined with Row-Level Security changes the game for protecting sensitive information at the database level while preserving precision in search and analytics.

Microsoft Presidio is an open-source data protection framework for detecting and anonymizing Personally Identifiable Information (PII). It scans text, images, and structured data, identifies sensitive entities using built-in or custom recognizers, and applies transformations such as masking or pseudonymization. When you integrate Presidio with database systems that support Row-Level Security, you control not just what fields are visible, but which rows a user is allowed to query based on policy.

Row-Level Security (RLS) enforces fine-grained access rules directly inside the database. Instead of filtering data in application code, RLS uses security predicates defined in SQL to determine row visibility per session. This design ensures that even if multiple services or users connect, unauthorized rows never appear in the result set.

The integration pattern is clear:

1. Identify sensitive fields with Microsoft Presidio before storage or query.
2. Tag records with classification metadata or sensitivity labels.
3. Enable Row-Level Security in your database (e.g., SQL Server, Azure Synapse, PostgreSQL) and bind access rules to those tags.
4. Maintain policies in SQL that match user identity, roles, or clearance level.
5. Audit and refine—Presidio detection improves with custom recognizers and feedback loops.

Use cases include finance systems isolating customer accounts, healthcare applications restricting patient records, and multi-tenant SaaS platforms enforcing tenant isolation while still centralizing infrastructure. By combining Presidio’s detection with RLS enforcement, developers build end-to-end pipelines that classify, store, and serve data under strict policy—without leaking sensitive rows through query exploits or coding mistakes.

Microsoft Presidio Row-Level Security removes the need to trust application filtering alone. Your protection lives where the data lives, at the lowest possible layer, with automated classification upstream. This approach reduces attack surface, meets compliance requirements, and simplifies policy enforcement in distributed systems.

Test this combination in a secure, controlled environment. Build a small dataset with tagged sensitive rows. Apply Presidio for classification. Enable RLS in your database engine. Observe how queries adapt automatically to user roles without changing application endpoints.

See what Microsoft Presidio Row-Level Security looks like in action. Try it on hoop.dev and spin up a working example in minutes.