Database users and the permissions they are granted may vary between PostgreSQL clusters. This is especially true if we do not directly administer the remote server. The role of user mappings is to overcome this obstacle by linking a local database user with a remote database user.

User mappings must be created for any local user that is going to utilize the remote server. Furthermore, these mappings are only valid for the remote server for which they're defined. In situations where all or most local users will be accessing remote data, this can be somewhat inconvenient. This is, however, a small price to pay for the security inherent in such a design.

In this recipe, we will create a user mapping to access our remote server.