## 51.8. `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; see `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.

Chapter 21 contains detailed information about user and privilege management.

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.

Table 51.8. `pg_authid` Columns

Column Type Description
`oid` `oid` Row identifier
`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. A replication role can initiate replication connections and create and drop replication slots.
`rolbypassrls` `bool` Role bypasses every row level security policy, see Section 5.8 for more information.
`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. The format depends on the form of encryption used.
`rolvaliduntil` `timestamptz` Password expiry time (only used for password authentication); null if no expiration

For an MD5 encrypted password, `rolpassword` 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`.

If the password is encrypted with SCRAM-SHA-256, it has the format:

    SCRAM-SHA-256$<iteration count>:<salt>$<StoredKey>:<ServerKey>

where `salt`, `StoredKey` and `ServerKey` are in Base64 encoded format. This format is the same as that specified by RFC 5803.

A password that does not follow either of those formats is assumed to be unencrypted.