21.5. Predefined Roles
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## 21.5. Predefined Roles #

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. For example:

    GRANT pg_signal_backend TO admin_user;

### Warning

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.

The predefined roles are described below. 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.

`pg_checkpoint` #

  `pg_checkpoint` allows executing the `CHECKPOINT` command.

`pg_create_subscription` #

  `pg_create_subscription` allows users with `CREATE` permission on the database to issue `CREATE SUBSCRIPTION`.

`pg_database_owner` #

  `pg_database_owner` always has exactly one implicit member: the current database owner. It cannot be granted membership in any role, and no role can be granted membership in `pg_database_owner`. However, like any other role, it can own objects and 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 possess those rights. Initially, this role owns the `public` schema, so each database owner governs local use of that schema.

`pg_maintain` #

  `pg_maintain` allows executing `VACUUM`, `ANALYZE`, `CLUSTER`, `REPACK`, `REFRESH MATERIALIZED VIEW`, `REINDEX`, and `LOCK TABLE` on all relations, as if having `MAINTAIN` rights on those objects.

`pg_monitor`
`pg_read_all_settings`
`pg_read_all_stats`
`pg_stat_scan_tables` #

  These 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.

  `pg_monitor` allows reading/executing 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_read_all_settings` allows reading all configuration variables, even those normally visible only to superusers.

  `pg_read_all_stats` allows reading all pg_stat_* views and use various statistics related extensions, even those normally visible only to superusers.

  `pg_stat_scan_tables` allows executing monitoring functions that may take `ACCESS SHARE` locks on tables, potentially for a long time (e.g., `pgrowlocks(text)` in the pgrowlocks extension).

`pg_read_all_data`
`pg_write_all_data` #

  `pg_read_all_data` allows reading all data (tables, views, sequences, large objects), as if having `SELECT` rights on those objects and `USAGE` rights on all schemas. This role does not bypass row-level security (RLS) policies. If RLS is being used, an administrator may wish to set `BYPASSRLS` on roles which this role is granted to.

  `pg_write_all_data` allows writing all data (tables, views, sequences, large objects), as if having `INSERT`, `UPDATE`, and `DELETE` rights on those objects and `USAGE` rights on all schemas. This role does not bypass row-level security (RLS) policies. If RLS is being used, an administrator may wish to set `BYPASSRLS` on roles which this role is granted to.

`pg_read_server_files`
`pg_write_server_files`
`pg_execute_server_program` #

  These 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. 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.

  `pg_read_server_files` allows reading files from any location the database can access on the server using `COPY` and other file-access functions.

  `pg_write_server_files` allows writing to files in any location the database can access on the server using `COPY` and other file-access functions.

  `pg_execute_server_program` allows executing programs on the database server as the user the database runs as using `COPY` and other functions which allow executing a server-side program.

`pg_signal_autovacuum_worker` #

  `pg_signal_autovacuum_worker` allows signaling autovacuum workers to cancel the current table's vacuum or terminate its session. See Section 9.29.2.

`pg_signal_backend` #

  `pg_signal_backend` allows signaling another backend to cancel a query or terminate its session. Note that this role does not permit signaling backends owned by a superuser. See Section 9.29.2.

`pg_use_reserved_connections` #

  `pg_use_reserved_connections` allows use of connection slots reserved via reserved_connections.

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