Postgresql pg_authid/pg_auth_members

pg_authid:

• The catalog pg_authid contains information about database authorization identifiers (roles). A role subsumes the concepts of "users" and "groups". A user is essentially just a role with the rolcanlogin flag set. Any role (with or without rolcanlogin) can have other roles as members of  pg_auth_members.
• Since this catalog contains passwords, it must not be publicly readable. pg_roles is a publicly readable view on pg_authid that blanks out the password field.
• Because user identities are cluster-wide, pg_authid is shared across all databases of a cluster: there is only one copy of pg_authid per cluster, not one per database.

pg_auth_members:

• The catalog pg_auth_members shows the membership relations between roles. Any non-circular set of relationships is allowed.
• Because user identities are cluster-wide, pg_auth_members is shared across all databases of a cluster: there is only one copy of pg_auth_members per cluster, not one per database.

pg_authid Columns:

Name	Type	Description
oid	oid	Row identifier (hidden attribute; must be explicitly selected)
rolname	name	Role name
rolsuper	bool	Role has superuser privileges
rolinherit	bool	Role automatically inherits privileges of roles it is a member of
rolcreaterole	bool	Role can create more roles
rolcreatedb	bool	Role can create databases
rolcanlogin	bool	Role can log in. That is, this role can be given as the initial session authorization identifier
rolreplication	bool	Role is a replication role. That is, this role can initiate streaming replication and set/unset the system backup mode usingpg_start_backup and pg_stop_backup
rolbypassrls	bool	Role bypasses every row level security policy,
rolconnlimit	int4	For roles that can log in, this sets maximum number of concurrent connections this role can make. -1 means no limit.
rolpassword	text	Password (possibly encrypted); null if none. If the password is encrypted, this column will begin with the string md5 followed by a 32-character hexadecimal MD5 hash. The MD5 hash will be of the user's password concatenated to their user name. For example, if user joe has password xyzzy, PostgreSQL will store the md5 hash of xyzzyjoe. A password that does not follow that format is assumed to be unencrypted.
rolvaliduntil	timestamptz	Password expiry time (only used for password authentication); null if no expiration

pg_auth_members Columns:

Name	Type	References	Description
roleid	oid	pg_authid.oid	ID of a role that has a member
mem ber	oid	pg_authid.oid	ID of a role that is a member of roleid
grantor	oid	pg_authid.oid	ID of the role that granted this membership
admin_option	bool		True if member can grant membership in roleid to others