REVOKE v11
Name
REVOKE
-- remove access privileges.
Synopsis
Description
The REVOKE
command revokes previously granted privileges from one or more roles. The key word PUBLIC
refers to the implicitly defined group of all roles.
See the description of the GRANT
command for the meaning of the privilege types.
Note that 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
. Thus, for example, revoking SELECT
privilege from PUBLIC
does not necessarily mean that all roles have lost SELECT
privilege on the object: those who have it granted directly or via another role will still have it.
If the privilege had been granted with the grant option, the grant option for the privilege is revoked as well as the privilege, itself.
If a user holds a privilege with grant option and has granted it to other users then the privileges held by those other users are called dependent privileges. If the privilege or the grant option held by the first user is being revoked and dependent privileges exist, those dependent privileges are also revoked if CASCADE
is specified, else the revoke action will fail. This recursive revocation only affects privileges that were granted through a chain of users that is traceable to the user that is the subject of this REVOKE
command. Thus, the affected users may effectively keep the privilege if it was also granted through other users.
Note
CASCADE
is not an option compatible with Oracle databases. By default Oracle always cascades dependent privileges, but Advanced Server requires the CASCADE
keyword to be explicitly given, otherwise the REVOKE
command will fail.
When revoking membership in a role, GRANT OPTION
is instead called ADMIN OPTION
, but the behavior is similar.
Notes
A user can only revoke privileges that were granted directly by that user. If, for example, user A
has granted a privilege with grant option to user B
, and user B
has in turned granted it to user C
, then user A
cannot revoke the privilege directly from C
. Instead, user A
could revoke the grant option from user B
and use the CASCADE
option so that the privilege is in turn revoked from user C
. For another example, if both A
and B
have granted the same privilege to C
, A
can revoke his own grant but not B
’s grant, so C
will still effectively have the privilege.
When a non-owner of an object attempts to REVOKE
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 revoke only those privileges for which the user has grant options. The REVOKE 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.)
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. Since all privileges ultimately come from the object owner (possibly indirectly via chains of grant options), it is possible for a superuser to revoke all privileges, but this may require use of CASCADE
as stated above.
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 command is performed as though it were issued by the containing 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 revoke privileges on t1
that are recorded as being granted by g1
. This would include grants made by u1
as well as by other members of role g1
.
If the role executing REVOKE
holds privileges indirectly via more than one role membership path, it is unspecified which containing role will be used to perform the command. In such cases it is best practice to use SET ROLE
to become the specific role you want to do the REVOKE
as. Failure to do so may lead to revoking privileges other than the ones you intended, or not revoking anything at all.
Note
The Advanced Server ALTER ROLE
command also supports syntax that revokes the system privileges required to create a public or private database link, or exemptions from fine-grained access control policies (DBMS_RLS
). The ALTER ROLE
syntax is functionally equivalent to the respective REVOKE
command, compatible with Oracle databases.
Examples
Revoke insert privilege for the public on table emp
:
Revoke all privileges from user mary
on view salesemp
:
Note that this actually means “revoke all privileges that I granted”.
Revoke membership in role admins
from user joe
:
Revoke CONNECT
privilege from user joe
:
Revoke CREATE DATABASE LINK
privilege from user joe
:
Revoke the EXEMPT ACCESS POLICY
privilege from user joe
:
See Also