How to Secure Your Database with Row Level Security
What row level security actually does, how to write policies that work, and how to prove your data is not exposed.
Published 24 Aug 2026 · Tested with Lovable as of 24 Aug 2026
Overview
Row level security decides, per row, who is allowed to read or change it. Without policies, a table is either unreachable or wide open.
Beginner explanation: It is a bouncer standing next to every row, checking who is asking.
Technical explanation: Enable RLS, grant the right table privileges, then write policies scoped to the signed-in user. Check role membership through a security-definer function rather than a subquery that can recurse.
Steps
- Confirm RLS is enabled on every table holding real data.
- Grant table privileges to the roles your policies allow.
- Write a read policy scoped to the owning user.
- Write separate write policies — being able to insert is not permission to read.
- Test with two different accounts.
:::tip Test with a second account, not just signed out. Cross-user leaks only show up with two real users. :::
What to check afterwards
- User A cannot read user B rows
- Signed-out visitors see only public data
- Every table with real data has RLS enabled
Common problems
- RLS on but no policies. Everything fails.
- Privileges missing. Permission errors even with correct policies.
- A policy of "true" for convenience. That is no protection at all.
Where people get stuck
If you have followed the steps and the result still is not right, the fastest path is usually to describe the exact behaviour you expected, the behaviour you got, and any error text, then ask for a fix in one focused follow-up prompt. If that loop is not converging, hand it over.
