You can use GraphQL with Cube's API to build a metrics dashboard with Postgres data, enabling clients to ask for exactly what they need and nothing more, making it easier to evolve APIs over time and providing powerful developer tools. To set up Cube with GraphQL and Postgres, you need to connect a database, generate a data schema, and run queries in the Cube Playground or GraphiQL interface. With GraphQL, you can add complex queries and retrieve specific data for your metrics dashboard. You can also use Cube Cloud's multi-tenancy support to enable role-based access control (RBAC) with JWT tokens, providing security and row-level access to your data.