PostgreSQL provides a set of predefined roles
that provide access to certain, commonly needed, privileged capabilities
and information. Administrators (including roles that have the
CREATEROLE privilege) can GRANT these
roles to users and/or other roles in their environment, providing those
users with access to the specified capabilities and information.
The predefined roles are described in Table 22.1. Note that the specific permissions for each of the roles may change in the future as additional capabilities are added. Administrators should monitor the release notes for changes.
Table 22.1. Predefined Roles
| Role | Allowed Access |
|---|---|
| pg_read_all_data | Read all data (tables, views, sequences), as if having
SELECT rights on those objects, and USAGE rights on
all schemas, even without having it explicitly. This role does not have
the role attribute BYPASSRLS set. If RLS is being
used, an administrator may wish to set BYPASSRLS on
roles which this role is GRANTed to. |
| pg_write_all_data | Write all data (tables, views, sequences), as if having
INSERT, UPDATE, and
DELETE rights on those objects, and USAGE rights on
all schemas, even without having it explicitly. This role does not have
the role attribute BYPASSRLS set. If RLS is being
used, an administrator may wish to set BYPASSRLS on
roles which this role is GRANTed to. |
| pg_read_all_settings | Read all configuration variables, even those normally visible only to superusers. |
| pg_read_all_stats | Read all pg_stat_* views and use various statistics related extensions, even those normally visible only to superusers. |
| pg_stat_scan_tables | Execute monitoring functions that may take ACCESS SHARE locks on tables,
potentially for a long time. |
| pg_monitor | Read/execute various monitoring views and functions.
This role is a member of pg_read_all_settings,
pg_read_all_stats and
pg_stat_scan_tables. |
| pg_database_owner | None. Membership consists, implicitly, of the current database owner. |
| pg_signal_backend | Signal another backend to cancel a query or terminate its session. |
| pg_read_server_files | Allow reading files from any location the database can access on the server with COPY and other file-access functions. |
| pg_write_server_files | Allow writing to files in any location the database can access on the server with COPY and other file-access functions. |
| pg_execute_server_program | Allow executing programs on the database server as the user the database runs as with COPY and other functions which allow executing a server-side program. |
| pg_checkpoint | Allow executing
the CHECKPOINT
command. |
| pg_use_reserved_connections | Allow use of connection slots reserved via reserved_connections. |
| pg_create_subscription | Allow users with CREATE permission on the
database to issue
CREATE SUBSCRIPTION. |
The pg_monitor, pg_read_all_settings,
pg_read_all_stats and pg_stat_scan_tables
roles are intended to allow administrators to easily configure a role for the
purpose of monitoring the database server. They grant a set of common privileges
allowing the role to read various useful configuration settings, statistics and
other system information normally restricted to superusers.
The pg_database_owner role has one implicit,
situation-dependent member, namely the owner of the current database. Like
any role, it can own objects or receive grants of access privileges.
Consequently, once pg_database_owner has rights within a
template database, each owner of a database instantiated from that template
will exercise those rights. pg_database_owner cannot be
a member of any role, and it cannot have non-implicit members. Initially,
this role owns the public schema, so each database owner
governs local use of the schema.
The pg_signal_backend role is intended to allow
administrators to enable trusted, but non-superuser, roles to send signals
to other backends. Currently this role enables sending of signals for
canceling a query on another backend or terminating its session. A user
granted this role cannot however send signals to a backend owned by a
superuser. See Section 9.27.2.
The pg_read_server_files, pg_write_server_files and
pg_execute_server_program roles are intended to allow administrators to have
trusted, but non-superuser, roles which are able to access files and run programs on the
database server as the user the database runs as. As these roles are able to access any file on
the server file system, they bypass all database-level permission checks when accessing files
directly and they could be used to gain superuser-level access, therefore
great care should be taken when granting these roles to users.
Care should be taken when granting these roles to ensure they are only used where needed and with the understanding that these roles grant access to privileged information.
Administrators can grant access to these roles to users using the
GRANT command, for example:
GRANT pg_signal_backend TO admin_user;