Need isolate usage example with supabase

[richard457]

Need isolate usage example with supabase

[rkistner]

From other conversations I gather:

1. You have some computation-heavy operations you want to do with the PowerSync database, so you want to run that in a background Isolate.
2. Supabase needs to run in the main Isolate (Init supabase inside isolate throw error supabase/supabase-flutter#1046).

So what I'd recommend:

1. Open and connect the PowerSyncDatabase in the main Isolate in the standard way, so all the Supabase-related logic will also be there.
2. Use db.isolateConnectionFactory() to create a connection in another Isolate.

Here's an example: https://gist.github.com/rkistner/e1067e51ad340f9447c4e55bc7bc96e1

The relevant bit for background isolate:

runInIsolate(IsolateConnectionFactory factory) async {
  return await Isolate.run(() async {
    var db = factory.open();
    var results = await db.getAll('select * from customers');
    return results;
  });
}

await runInIsolate(db.isolateConnectionFactory());

This example uses Isolate.run for a short-lived Isolate, but the same approach would work for long-lived Isolates using Isolate.spawn.

Note that inside the Isolate, the database is an instance of a sqlite_async SqliteConnection, rather than a full PowerSyncDatabase. All the query methods remain the same, and that should be all you need to work with the database.