> ## Documentation Index
> Fetch the complete documentation index at: https://powersync-document-db.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# RLS and Sync Streams

> How PowerSync Sync Streams work alongside Supabase Row Level Security.

PowerSync's [Sync Streams](/sync/streams/overview) (or legacy [Sync Rules](/sync/rules/overview)) and Supabase's support for [Row Level Security (RLS)](https://supabase.com/docs/guides/auth/row-level-security) can be used in conjunction. Here are some high level similarities and differences:

* RLS should be used as the authoritative set of security rules applied to your users' CRUD operations that reach Postgres.
* Sync Streams (or legacy Sync Rules) are only applied for data that is to be downloaded to clients. They do not apply to uploaded data.
  * Sync Streams / Sync Rules can typically be considered to be complementary to RLS, and will generally mirror your RLS setup.

<Note>
  Supabase tables are often created with auto-increment IDs. For easiest use of PowerSync, make sure to convert them to text IDs as detailed [**here**](/sync/advanced/client-id)**.**
</Note>

### Example

The [Supabase + PowerSync guide](/integrations/supabase/guide#create-the-demo-database-schema) sets up RLS policies for the to-do list demo app:

```sql theme={null}
create policy "owned lists" on public.lists
  for all to authenticated
  using (auth.uid() = owner_id);

create policy "todos in owned lists" on public.todos
  for all to authenticated
  using (
    auth.uid() in (
      select lists.owner_id from public.lists where lists.id = todos.list_id
    )
  );
```

`auth.uid()` in a Supabase RLS policy maps to:

* `auth.user_id()` in [Sync Streams](/sync/streams/overview)
* `request.user_id()` (previously `token_parameters.user_id`) in legacy [Sync Rules](/sync/rules/overview)

If you compare these policies to the Sync Config in the guide, you'll see the access patterns mirror each other.

If you have any questions, join us on [our community Discord](https://discord.gg/powersync) where our team is always available to help.