GRANT() SQL Commands GRANT()
NAME
GRANT - define access privileges
SYNOPSIS
GRANT { { SELECT | INSERT | UPDATE | DELETE | REFERENCES | TRIGGER }
[,...] | ALL [ PRIVILEGES ] }
ON [ TABLE ] tablename [, ...]
TO { [ GROUP ] rolename | PUBLIC } [, ...] [ WITH GRANT OPTION ]
GRANT { { USAGE | SELECT | UPDATE }
[,...] | ALL [ PRIVILEGES ] }
ON SEQUENCE sequencename [, ...]
TO { [ GROUP ] rolename | PUBLIC } [, ...] [ WITH GRANT OPTION ]
GRANT { { CREATE | CONNECT | TEMPORARY | TEMP } [,...] | ALL [ PRIVILEGES ] }
ON DATABASE dbname [, ...]
TO { [ GROUP ] rolename | PUBLIC } [, ...] [ WITH GRANT OPTION ]
GRANT { EXECUTE | ALL [ PRIVILEGES ] }
ON FUNCTION funcname ( [ [ argmode ] [ argname ] argtype [, ...] ] ) [, ...]
TO { [ GROUP ] rolename | PUBLIC } [, ...] [ WITH GRANT OPTION ]
GRANT { USAGE | ALL [ PRIVILEGES ] }
ON LANGUAGE langname [, ...]
TO { [ GROUP ] rolename | PUBLIC } [, ...] [ WITH GRANT OPTION ]
GRANT { { CREATE | USAGE } [,...] | ALL [ PRIVILEGES ] }
ON SCHEMA schemaname [, ...]
TO { [ GROUP ] rolename | PUBLIC } [, ...] [ WITH GRANT OPTION ]
GRANT { CREATE | ALL [ PRIVILEGES ] }
ON TABLESPACE tablespacename [, ...]
TO { [ GROUP ] rolename | PUBLIC } [, ...] [ WITH GRANT OPTION ]
GRANT role [, ...] TO rolename [, ...] [ WITH ADMIN OPTION ]
DESCRIPTION
The GRANT command has two basic variants: one that grants privileges on
a database object (table, view, sequence, database, function, procedu-
ral 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.
As of PostgreSQL 8.1, the concepts of users and groups have been uni-
fied 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.
GRANT ON DATABASE OBJECTS
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.
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 can-
not 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 described by a grantable privilege; it is inherent in
the owner, and cannot be granted or revoked. 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, schemas, and tablespaces; CONNECT privilege and TEMP
table creation privilege for databases; EXECUTE privilege for func-
tions; 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 win-
dow in which another user can use the object.)
The possible privileges are:
SELECT Allows SELECT [select(7)] from any column of the specified ta-
ble, view, or sequence. Also allows the use of COPY [copy(7)]
TO. This privilege is also needed to reference existing column
values in UPDATE [update(7)] or DELETE [delete(7)]. For
sequences, this privilege also allows the use of the currval
function.
INSERT Allows INSERT [insert(7)] of a new row into the specified table.
Also allows COPY [copy(7)] FROM.
UPDATE Allows UPDATE [update(7)] of any column 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, in addition to the SELECT privilege. For
sequences, this privilege allows the use of the nextval and set-
val functions.
DELETE Allows DELETE [delete(7)] 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.)
REFERENCES
To create a foreign key constraint, it is necessary to have this
privilege on both the referencing and referenced tables.
TRIGGER
Allows the creation of a trigger on the specified table. (See
the CREATE TRIGGER [create_trigger(7)] statement.)
CREATE 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.)
CONNECT
Allows the user to connect to the specified database. This priv-
ilege is checked at connection startup (in addition to checking
any restrictions imposed by pg_hba.conf).
TEMPORARY
TEMP Allows temporary tables to be created while using the specified
database.
EXECUTE
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.)
USAGE For procedural languages, allows the use of the specified lan-
guage for the creation of functions in that language. This is
the only type of privilege that is applicable to procedural lan-
guages.
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.
ALL PRIVILEGES
Grant all of the available privileges at once. The PRIVILEGES
key word is optional in PostgreSQL, though it is required by
strict SQL.
The privileges required by other commands are listed on the reference
page of the respective command.
GRANT ON ROLES
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 con-
veys the privileges granted to a role to each of its members.
If WITH ADMIN OPTION is specified, the member can in turn grant member-
ship 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 any-
one. 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.
NOTES
The REVOKE [revoke(7)] command is used to revoke access privileges.
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 specif-
ically named in the command are not held. (In principle these state-
ments 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 privi-
leges 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 con-
taining 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 permis-
sions to any sequences used by the table, including sequences tied to
SERIAL columns. Permissions on sequence must be set separately.
Currently, PostgreSQL does not support granting or revoking privileges
for individual columns of a table. One possible workaround is to cre-
ate a view having just the desired columns and then grant privileges to
that view.
Use psql(1)'s \z command to obtain information about existing privi-
leges, for example:
=> \z mytable
Access privileges for database "lusitania"
Schema | Name | Type | Access privileges
--------+---------+-------+---------------------------------------------------
public | mytable | table | {miriam=arwdxt/miriam,=r/miriam,admin=arw/miriam}
(1 row)
The entries shown by \z 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
x -- REFERENCES
t -- TRIGGER
X -- EXECUTE
U -- USAGE
C -- CREATE
c -- CONNECT
T -- TEMPORARY
arwdxt -- ALL PRIVILEGES (for tables)
* -- grant option for preceding privilege
/yyyy -- role that granted this privilege
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 admin;
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=arwdxt/miriam}) and then modify them per the specified request.
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.
EXAMPLES
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;
COMPATIBILITY
According to the SQL standard, the PRIVILEGES key word in ALL PRIVI-
LEGES is required. The SQL standard does not support setting the privi-
leges on more than one object per command.
PostgreSQL allows an object owner to revoke his own ordinary privi-
leges: for example, a table owner can make the table read-only to him-
self by revoking his own INSERT, UPDATE, and DELETE privileges. This is
not possible according to the SQL standard. The reason is that Post-
greSQL treats the owner's privileges as having been granted by the
owner to himself; therefore he can revoke them too. In the SQL stan-
dard, the owner's privileges are granted by an assumed entity ``_SYS-
TEM''. Not being ``_SYSTEM'', the owner cannot revoke these rights.
PostgreSQL does not support the SQL-standard functionality of setting
privileges for individual columns.
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 Post-
greSQL extensions.
SEE ALSO
REVOKE [revoke(7)]
SQL - Language Statements 2010-03-12 GRANT()
Hypertext Manpage Browser (grant)
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