On Apache
Under GNU General Public License
2012-05-25 19:43 @38.107.179.240 Crawled by CCBot/1.0 (+http://www.commoncrawl.org/bot.html)
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, 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.
As of 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.
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, includ-
ing 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 cre-
ated 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 functions; and USAGE privilege for languages. The object owner can of
course revoke these privileges. (For maximum security, issue the REVOKE in the same trans-
action that creates the object; then there is no window in which another user can use the
object.)
The possible privileges are:
SELECT Allows SELECT [select(7)] from any column of the specified table, 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 ref-
erence table columns to determine which rows to update, and/or to compute new val-
ues 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 setval 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 ref-
erence 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 privilege 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 language for the creation
of functions in that language. This is the only type of privilege that is applica-
ble 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.
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 respec-
tive 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 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.
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 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 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 create 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 privileges, 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 PRIVILEGES is required. The
SQL standard does not support setting the privileges on more than one object per command.
PostgreSQL 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,
and DELETE privileges. This is not possible according to the SQL standard. The reason is
that PostgreSQL treats the owner's privileges as having been granted by the owner to him-
self; 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.
PostgreSQL does not support the SQL-standard functionality of setting privileges for indi-
vidual 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 PostgreSQL extensions.
SEE ALSO
REVOKE [revoke(7)]
SQL - Language Statements 2011-09-22 GRANT()
Generated by $Id: phpMan.php,v 4.49 2006/02/26 13:18:18 chedong Exp $ Author: Che Dong
On Apache
Under GNU General Public License
2012-05-25 19:43 @38.107.179.240 Crawled by CCBot/1.0 (+http://www.commoncrawl.org/bot.html)