GRANT { { SELECT | INSERT | UPDATE | DELETE | TRUNCATE | REFERENCES | TRIGGER }
[, ...] | ALL [ PRIVILEGES ] }
ON { [ TABLE ] table_name [, ...]
| ALL TABLES IN SCHEMA schema_name [, ...] }
TO { [ GROUP ] role_name | PUBLIC } [, ...] [ WITH GRANT OPTION ]
GRANT { { SELECT | INSERT | UPDATE | REFERENCES } ( column [, ...] )
[, ...] | ALL [ PRIVILEGES ] ( column [, ...] ) }
ON [ TABLE ] table_name [, ...]
TO { [ GROUP ] role_name | PUBLIC } [, ...] [ WITH GRANT OPTION ]
GRANT { { USAGE | SELECT | UPDATE }
[, ...] | ALL [ PRIVILEGES ] }
ON { SEQUENCE sequence_name [, ...]
| ALL SEQUENCES IN SCHEMA schema_name [, ...] }
TO { [ GROUP ] role_name | PUBLIC } [, ...] [ WITH GRANT OPTION ]
GRANT { { CREATE | CONNECT | TEMPORARY | TEMP } [, ...] | ALL [ PRIVILEGES ] }
ON DATABASE database_name [, ...]
TO { [ GROUP ] role_name | PUBLIC } [, ...] [ WITH GRANT OPTION ]
GRANT { USAGE | ALL [ PRIVILEGES ] }
ON FOREIGN DATA WRAPPER fdw_name [, ...]
TO { [ GROUP ] role_name | PUBLIC } [, ...] [ WITH GRANT OPTION ]
GRANT { USAGE | ALL [ PRIVILEGES ] }
ON FOREIGN SERVER server_name [, ...]
TO { [ GROUP ] role_name | PUBLIC } [, ...] [ WITH GRANT OPTION ]
GRANT { EXECUTE | ALL [ PRIVILEGES ] }
ON { FUNCTION function_name ( [ [ argmode ] [ arg_name ] arg_type [, ...] ] ) [, ...]
| ALL FUNCTIONS IN SCHEMA schema_name [, ...] }
TO { [ GROUP ] role_name | PUBLIC } [, ...] [ WITH GRANT OPTION ]
GRANT { USAGE | ALL [ PRIVILEGES ] }
ON LANGUAGE lang_name [, ...]
TO { [ GROUP ] role_name | PUBLIC } [, ...] [ WITH GRANT OPTION ]
GRANT { { SELECT | UPDATE } [, ...] | ALL [ PRIVILEGES ] }
ON LARGE OBJECT loid [, ...]
TO { [ GROUP ] role_name | PUBLIC } [, ...] [ WITH GRANT OPTION ]
GRANT { { CREATE | USAGE } [, ...] | ALL [ PRIVILEGES ] }
ON SCHEMA schema_name [, ...]
TO { [ GROUP ] role_name | PUBLIC } [, ...] [ WITH GRANT OPTION ]
GRANT { CREATE | ALL [ PRIVILEGES ] }
ON TABLESPACE tablespace_name [, ...]
TO { [ GROUP ] role_name | PUBLIC } [, ...] [ WITH GRANT OPTION ]
GRANT role_name [, ...] TO role_name [, ...] [ WITH ADMIN OPTION ]Note: The following description applies both to Postgres-XC and PostgreSQL if not described explicitly.
The GRANT command has two basic variants: one that grants privileges on a database object (table, column, view, foreign table, sequence, database, foreign-data wrapper, foreign server, function, procedural language, schema, or tablespace), and one that grants membership in a role. These variants are similar in many ways, but they are different enough to be described separately.
This variant of the GRANT command gives specific privileges on a database object to one or more roles. These privileges are added to those already granted, if any.
There is also an option to grant privileges on all objects of the same type within one or more schemas. This functionality is currently supported only for tables, sequences, and functions (but note that ALL TABLES is considered to include views and foreign tables).
The key word PUBLIC indicates that the privileges are to be granted to all roles, including those that might be created later. PUBLIC can be thought of as an implicitly defined group that always includes all roles. Any particular role will have the sum of privileges granted directly to it, privileges granted to any role it is presently a member of, and privileges granted to PUBLIC.
If WITH GRANT OPTION is specified, the recipient of the privilege can in turn grant it to others. Without a grant option, the recipient cannot do that. Grant options cannot be granted to PUBLIC.
There is no need to grant privileges to the owner of an object (usually the user that created it), as the owner has all privileges by default. (The owner could, however, choose to revoke some of his own privileges for safety.)
The right to drop an object, or to alter its definition in any way, is not treated as a grantable privilege; it is inherent in the owner, and cannot be granted or revoked. (However, a similar effect can be obtained by granting or revoking membership in the role that owns the object; see below.) The owner implicitly has all grant options for the object, too.
Depending on the type of object, the initial default privileges might include granting some privileges to PUBLIC. The default is no public access for tables, columns, schemas, and tablespaces; CONNECT privilege and TEMP table creation privilege for databases; EXECUTE privilege for functions; and USAGE privilege for languages. The object owner can 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 can use the object.) Also, these initial default privilege settings can be changed using the ALTER DEFAULT PRIVILEGES command.
The possible privileges are:
Allows SELECT from
any column, or the specific columns listed, of the specified table,
view, or sequence.
Also allows the use of
COPY TO.
This privilege is also needed to reference existing column values in
UPDATE or
DELETE.
For sequences, this privilege also allows the use of the
currval function.
For large objects, this privilege allows the object to be read.
Allows INSERT of a new row into the specified table. If specific columns are listed, only those columns may be assigned to in the INSERT command (other columns will therefore receive default values). Also allows COPY FROM.
Allows UPDATE of any
column, or the specific columns listed, of the specified table.
(In practice, any nontrivial UPDATE command will require
SELECT privilege as well, since it must reference table
columns to determine which rows to update, and/or to compute new
values for columns.)
SELECT ... FOR UPDATE
and SELECT ... FOR SHARE
also require this privilege on at least one column, in addition to the
SELECT privilege. For sequences, this
privilege allows the use of the nextval and
setval functions.
For large objects, this privilege allows writing or truncating the
object.
Allows DELETE of a row from the specified table. (In practice, any nontrivial DELETE command will require SELECT privilege as well, since it must reference table columns to determine which rows to delete.)
Allows TRUNCATE on the specified table.
To create a foreign key constraint, it is necessary to have this privilege on both the referencing and referenced columns. The privilege may be granted for all columns of a table, or just specific columns.
Allows the creation of a trigger on the specified table. (See the CREATE TRIGGER statement.)
For databases, allows new schemas to be created within the database.
For schemas, allows new objects to be created within the schema. To rename an existing object, you must own the object and have this privilege for the containing schema.
For tablespaces, allows tables, indexes, and temporary files to be created within the tablespace, and allows databases to be created that have the tablespace as their default tablespace. (Note that revoking this privilege will not alter the placement of existing objects.)
Allows the user to connect to the specified database. This privilege is checked at connection startup (in addition to checking any restrictions imposed by pg_hba.conf).
Allows temporary tables to be created while using the specified database.
Allows the use of the specified function and the use of any operators that are implemented on top of the function. This is the only type of privilege that is applicable to functions. (This syntax works for aggregate functions, as well.)
For procedural languages, allows the use of the specified language for the creation of functions in that language. This is the only type of privilege that is applicable to procedural languages.
For schemas, allows access to objects contained in the specified schema (assuming that the objects' own privilege requirements are also met). Essentially this allows the grantee to "look up" objects within the schema. Without this permission, it is still possible to see the object names, e.g. by querying the system tables. Also, after revoking this permission, existing backends might have statements that have previously performed this lookup, so this is not a completely secure way to prevent object access.
For sequences, this privilege allows the use of the
currval and nextval functions.
For foreign-data wrappers, this privilege enables the grantee to create new servers using that foreign-data wrapper.
For servers, this privilege enables the grantee to create, alter, and drop his own user's user mappings associated with that server. Also, it enables the grantee to query the options of the server and associated user mappings.
Grant all of the available privileges at once. The PRIVILEGES key word is optional in Postgres-XC, though it is required by strict SQL.
The privileges required by other commands are listed on the reference page of the respective command.
This variant of the GRANT command grants membership in a role to one or more other roles. Membership in a role is significant because it conveys the privileges granted to a role to each of its members.
If WITH ADMIN OPTION is specified, the member can in turn grant membership in the role to others, and revoke membership in the role as well. Without the admin option, ordinary users cannot do that. However, database superusers can grant or revoke membership in any role to anyone. Roles having CREATEROLE privilege can grant or revoke membership in any role that is not a superuser.
Unlike the case with privileges, membership in a role cannot be granted to PUBLIC. Note also that this form of the command does not allow the noise word GROUP.
The REVOKE command is used to revoke access privileges.
Since PostgreSQL 8.1, the concepts of users and groups have been unified into a single kind of entity called a role. It is therefore no longer necessary to use the keyword GROUP to identify whether a grantee is a user or a group. GROUP is still allowed in the command, but it is a noise word.
A user may perform SELECT, INSERT, etc. on a column if he holds that privilege for either the specific column or its whole table. Granting the privilege at the table level and then revoking it for one column will not do what you might wish: the table-level grant is unaffected by a column-level operation.
When a non-owner of an object attempts to GRANT privileges on the object, the command will fail outright if the user has no privileges whatsoever on the object. As long as some privilege is available, the command will proceed, but it will grant only those privileges for which the user has grant options. The GRANT ALL PRIVILEGES forms will issue a warning message if no grant options are held, while the other forms will issue a warning if grant options for any of the privileges specifically named in the command are not held. (In principle these statements apply to the object owner as well, but since the owner is always treated as holding all grant options, the cases can never occur.)
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.
If a superuser chooses to issue a GRANT or REVOKE command, the command is performed as though it were issued by the owner of the affected object. In particular, privileges granted via such a command will appear to have been granted by the object owner. (For role membership, the membership appears to have been granted by the containing role itself.)
GRANT and REVOKE can also be done by a role that is not the owner of the affected object, but is a member of the role that owns the object, or is a member of a role that holds privileges WITH GRANT OPTION on the object. In this case the privileges will be recorded as having been granted by the role that actually owns the object or holds the privileges WITH GRANT OPTION. For example, if table t1 is owned by role g1, of which role u1 is a member, then u1 can grant privileges on t1 to u2, but those privileges will appear to have been granted directly by g1. Any other member of role g1 could revoke them later.
If the role executing GRANT holds the required privileges indirectly via more than one role membership path, it is unspecified which containing role will be recorded as having done the grant. In such cases it is best practice to use SET ROLE to become the specific role you want to do the GRANT as.
Granting permission on a table does not automatically extend permissions to any sequences used by the table, including sequences tied to SERIAL columns. Permissions on sequences must be set separately.
Use psql's \dp command to obtain information about existing privileges for tables and columns. For example:
=> \dp mytable
Access privileges
Schema | Name | Type | Access privileges | Column access privileges
--------+---------+-------+-----------------------+--------------------------
public | mytable | table | miriam=arwdDxt/miriam | col1:
: =r/miriam : miriam_rw=rw/miriam
: admin=arw/miriam
(1 row)The entries shown by \dp are interpreted thus:
rolename=xxxx -- privileges granted to a role
=xxxx -- privileges granted to PUBLIC
r -- SELECT ("read")
w -- UPDATE ("write")
a -- INSERT ("append")
d -- DELETE
D -- TRUNCATE
x -- REFERENCES
t -- TRIGGER
X -- EXECUTE
U -- USAGE
C -- CREATE
c -- CONNECT
T -- TEMPORARY
arwdDxt -- ALL PRIVILEGES (for tables, varies for other objects)
* -- grant option for preceding privilege
/yyyy -- role that granted this privilegeThe 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 admin; GRANT SELECT (col1), UPDATE (col1) ON mytable TO miriam_rw;
For non-table objects there are other \d commands that can display their privileges.
If the "Access privileges" column is empty for a given object, it means the object has default privileges (that is, its privileges column is null). Default privileges always include all privileges for the owner, and can 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=arwdDxt/miriam}) and then modify them per the specified request. Similarly, entries are shown in "Column access privileges" only for columns with nondefault privileges. (Note: for this purpose, "default privileges" always means the built-in default privileges for the object's type. An object whose privileges have been affected by an ALTER DEFAULT PRIVILEGES command will always be shown with an explicit privilege entry that includes the effects of the ALTER.)
Notice that the owner's implicit grant options are not marked in the access privileges display. A * will appear only when grant options have been explicitly granted to someone.
Grant insert privilege to all users on table films:
GRANT INSERT ON films TO PUBLIC;
Grant all available privileges to user manuel on view kinds:
GRANT ALL PRIVILEGES ON kinds TO manuel;
Note that while the above will indeed grant all privileges if executed by a superuser or the owner of kinds, when executed by someone else it will only grant those permissions for which the someone else has grant options.
Grant membership in role admins to user joe:
GRANT admins TO joe;
According to the SQL standard, the PRIVILEGES key word in ALL PRIVILEGES is required. The SQL standard does not support setting the privileges on more than one object per command.
Postgres-XC allows an object owner to revoke his own ordinary privileges: for example, a table owner can make the table read-only to himself by revoking his own INSERT, UPDATE, DELETE, and TRUNCATE privileges. This is not possible according to the SQL standard. The reason is that Postgres-XC treats the owner's privileges as having been granted by the owner to himself; therefore he can revoke them too. In the SQL standard, the owner's privileges are granted by an assumed entity "_SYSTEM". Not being "_SYSTEM", the owner cannot revoke these rights.
The SQL standard provides for a USAGE privilege on other kinds of objects: character sets, collations, translations, domains.
Privileges on databases, tablespaces, schemas, and languages are Postgres-XC extensions.