It is frequently convenient to group users together to ease management of privileges: that way, privileges can be granted to, or revoked from, a group as a whole. In Postgres Pro this is done by creating a role that represents the group, and then granting membership in the group role to individual user roles.

To set up a group role, first create the role:

CREATE ROLE name;

Typically a role being used as a group would not have the LOGIN attribute, though you can set it if you wish.

Once the group role exists, you can add and remove members using the GRANT and REVOKE commands:

GRANT group_role TO role1, ... ;
REVOKE group_role FROM role1, ... ;

You can grant membership to other group roles, too (since there isn't really any distinction between group roles and non-group roles). The database will not let you set up circular membership loops. Also, it is not permitted to grant membership in a role to PUBLIC.

The members of a group role can use the privileges of the role in two ways. First, member roles that have been granted membership with the SET option can do SET ROLE to temporarily “become” the group role. In this state, the database session has access to the privileges of the group role rather than the original login role, and any database objects created are considered owned by the group role not the login role. Second, member roles that have been granted membership with the INHERIT option automatically have use of the privileges of those directly or indirectly a member of, though the chain stops at memberships lacking the inherit option. As an example, suppose we have done:

CREATE ROLE joe LOGIN;
CREATE ROLE admin;
CREATE ROLE wheel;
CREATE ROLE island;
GRANT admin TO joe WITH INHERIT TRUE;
GRANT wheel TO admin WITH INHERIT FALSE;
GRANT island TO joe WITH INHERIT TRUE, SET FALSE;

Immediately after connecting as role joe, a database session will have use of privileges granted directly to joe plus any privileges granted to admin and island, because joe “inherits” those privileges. However, privileges granted to wheel are not available, because even though joe is indirectly a member of wheel, the membership is via admin which was granted using WITH INHERIT FALSE. After:

SET ROLE admin;

the session would have use of only those privileges granted to admin, and not those granted to joe or island. After:

SET ROLE wheel;

the session would have use of only those privileges granted to wheel, and not those granted to either joe or admin. The original privilege state can be restored with any of:

SET ROLE joe;
SET ROLE NONE;
RESET ROLE;

The role attributes LOGIN, SUPERUSER, CREATEDB, and CREATEROLE can be thought of as special privileges, but they are never inherited as ordinary privileges on database objects are. You must actually SET ROLE to a specific role having one of these attributes in order to make use of the attribute. Continuing the above example, we might choose to grant CREATEDB and CREATEROLE to the admin role. Then a session connecting as role joe would not have these privileges immediately, only after doing SET ROLE admin.

To destroy a group role, use DROP ROLE:

DROP ROLE name;

Any memberships in the group role are automatically revoked (but the member roles are not otherwise affected).