GRANT

Description

The GRANT command gives specific permissions on an object (table, view, sequence, database, function, procedural language, or schema) to one or more users or groups of users. These permissions are added to those already granted, if any.

The key word PUBLIC indicates that the privileges are to be granted to all users, including those that may be created later. PUBLIC may be thought of as an implicitly defined group that always includes all users. Note that any particular user will have the sum of privileges granted directly to him, privileges granted to any group he is presently a member of, and privileges granted to PUBLIC.

There is no need to grant privileges to the creator of an object, as the creator has all privileges by default. (The creator could, however, choose to revoke some of his own privileges for safety.) Note that the ability to grant and revoke privileges is inherent in the creator and cannot be lost. The right to drop an object, or to alter it in any way not described by a grantable right, is likewise inherent in the creator, and cannot be granted or revoked.

Depending on the type of object, the initial default privileges may include granting some privileges to PUBLIC. The default is no public access for tables and schemas; TEMP table creation privilege for databases; EXECUTE privilege for functions; and USAGE privilege for languages. The object creator may of course revoke these privileges. (For maximum security, issue the REVOKE in the same transaction that creates the object; then there is no window in which another user may use the object.)

The possible privileges are:

The privileges required by other commands are listed on the reference page of the respective command.

Notes

The REVOKE command is used to revoke access privileges.

It should be noted that database superusers can access all objects regardless of object privilege settings. This is comparable to the rights of root in a Unix system. As with root, it's unwise to operate as a superuser except when absolutely necessary.

Currently, to grant privileges in PostgreSQL to only a few columns, you must create a view having the desired columns and then grant privileges to that view.

Use psql's \dp command to obtain information about existing privileges, for example:

lusitania=> \dp mytable
         Access privileges for database "lusitania"
  Schema |  Table  |           Access privileges
 --------+---------+---------------------------------------
  public | mytable | {=r,miriam=arwdRxt,"group todos=arw"}
 (1 row)

The entries shown by \dp are interpreted thus:

              =xxxx -- privileges granted to PUBLIC
          uname=xxxx -- privileges granted to a user
    group gname=xxxx -- privileges granted to a group
 
                   r -- SELECT ("read")
                   w -- UPDATE ("write")
                   a -- INSERT ("append")
                   d -- DELETE
                   R -- RULE
                   x -- REFERENCES
                   t -- TRIGGER
                   X -- EXECUTE
                   U -- USAGE
                   C -- CREATE
                   T -- TEMPORARY
             arwdRxt -- ALL PRIVILEGES (for tables)

The above example display would be seen by user miriam after creating table mytable and doing

GRANT SELECT ON mytable TO PUBLIC;
 GRANT SELECT,UPDATE,INSERT ON mytable TO GROUP todos;

If the "Access privileges" column is empty for a given object, it means the object has default privileges (that is, its privileges field is NULL). Default privileges always include all privileges for the owner, and may include some privileges for PUBLIC depending on the object type, as explained above. The first GRANT or REVOKE on an object will instantiate the default privileges (producing, for example, {=,miriam=arwdRxt}) and then modify them per the specified request.

Examples

Grant insert privilege to all users on table films:

GRANT INSERT ON films TO PUBLIC;

Grant all privileges to user manuel on view kinds:

GRANT ALL PRIVILEGES ON kinds TO manuel;

Compatibility

GRANT privilege [, ...]
     ON object [ ( column [, ...] ) ] [, ...]
     TO { PUBLIC | username [, ...] } [ WITH GRANT OPTION ]

See Also

REVOKE