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Supabase RLS: securing your data like a senior engineer
Row Level Security policies, auth.uid() patterns & the common holes that expose production data
Row Level Security is a PostgreSQL feature that filters rows before they reach your application. When RLS is enabled on a table, every query automatically gets a WHERE clause appended based on your policies. The key function is auth.uid() — Supabase injects the authenticated user's ID into the PostgreSQL session so your policies can reference it. Without RLS enabled, anyone with your anon key can read all rows in all tables.
Key Points
- ▸RLS adds automatic WHERE clauses to every query
- ▸auth.uid() returns the logged-in user's ID
- ▸Policies are AND-ed together — all must pass
- ▸Service role key bypasses RLS — never expose it client-side