1---
2title: Optimize RLS Policies for Performance
3impact: HIGH
4impactDescription: 5-10x faster RLS queries with proper patterns
5tags: rls, performance, security, optimization
6---
7 
8## Optimize RLS Policies for Performance
9 
10Poorly written RLS policies can cause severe performance issues. Use subqueries and indexes strategically.
11 
12**Incorrect (function called for every row):**
13 
14```sql
15create policy orders_policy on orders
16  using (auth.uid() = user_id);  -- auth.uid() called per row!
17 
18-- With 1M rows, auth.uid() is called 1M times
19```
20 
21**Correct (wrap functions in SELECT):**
22 
23```sql
24create policy orders_policy on orders
25  using ((select auth.uid()) = user_id);  -- Called once, cached
26 
27-- 100x+ faster on large tables
28```
29 
30Use security definer functions for complex checks:
31 
32`SECURITY DEFINER` functions run with the creator's privileges and bypass RLS on any tables they touch — which is what makes them useful for internal lookups, but also what makes them dangerous if misused. Always include an explicit `auth.uid()` check inside the function body, keep them in a non-exposed schema, and revoke `EXECUTE` from any role that shouldn't call them directly.
33 
34```sql
35-- Create helper function in a private schema
36create or replace function private.is_team_member(team_id bigint)
37returns boolean
38language sql
39security definer
40set search_path = ''
41as $$
42  select exists (
43    select 1 from public.team_members
44    -- always check the calling user's identity inside the function
45    where team_id = $1 and user_id = (select auth.uid())
46  );
47$$;
48 
49-- Revoke direct execution from public roles
50revoke execute on function private.is_team_member(bigint) from PUBLIC, anon, authenticated, service_role;
51 
52-- Use in policy (indexed lookup, not per-row check)
53create policy team_orders_policy on orders
54  using ((select private.is_team_member(team_id)));
55```
56 
57Always add indexes on columns used in RLS policies:
58 
59```sql
60create index orders_user_id_idx on orders (user_id);
61```
62 
63Reference: [RLS Performance](https://supabase.com/docs/guides/database/postgres/row-level-security#rls-performance-recommendations)
64