> ## Documentation Index
> Fetch the complete documentation index at: https://docs.powersync.com/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

Continuing with the schema set up during the guide, below are the RLS policies for the to-do list app:

```sql theme={null}
alter table public.lists
  enable row level security;

alter table public.todos
  enable row level security;

create policy "owned lists" on public.lists for ALL using (
  auth.uid() = owner_id
);

create policy "todos in owned lists" on public.todos for ALL using (
  auth.uid() IN (
    SELECT lists.owner_id FROM 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 to your sync config, you'll see the access patterns are quite similar.

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