Authentication in ADPG
Authentication is the process of verifying the identity of a user who wants to establish the connection with the server. The server determines whether a client application or a user that runs the client application is permitted to connect with the specified user name. ADPG uses roles to manage access privileges. In the PostgreSQL terminology, a user is a role with the LOGIN privilege.
PostgreSQL roles are separate from operating system users. A database server can accept remote connections with users who have no local operating system account.