~ubuntu-branches/ubuntu/oneiric/postgresql-9.1/oneiric-security

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

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PUBLIC\&. Thus, for example, revoking

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SELECT

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privilege from

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PUBLIC

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does not necessarily mean that all roles have lost

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SELECT

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privilege on the object: those who have it granted directly or via another role will still have it\&. Similarly, revoking

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SELECT

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from a user might not prevent that user from using

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SELECT

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PUBLIC

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or another membership role still has

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SELECT

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rights\&.

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.PP

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GRANT OPTION FOR

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is specified, only the grant option for the privilege is revoked, not the privilege itself\&. Otherwise, both the privilege and the grant option are revoked\&.

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.PP

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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

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CASCADE

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is specified; if it is not, 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

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REVOKE

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command\&. Thus, the affected users might effectively keep the privilege if it was also granted through other users\&.

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.PP

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When revoking privileges on a table, the corresponding column privileges (if any) are automatically revoked on each column of the table, as well\&.

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.PP

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When revoking membership in a role,

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GRANT OPTION

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is instead called

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ADMIN OPTION, but the behavior is similar\&. Note also that this form of the command does not allow the noise word

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GROUP\&.

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.SH "NOTES"

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.PP

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Use

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\fBpsql\fR(1)\(aqs

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\edp

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command to display the privileges granted on existing tables and columns\&. See

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\fBGRANT\fR(7)

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for information about the format\&. For non\-table objects there are other

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\ed

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commands that can display their privileges\&.

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.PP

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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

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CASCADE

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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\(aqs grant, so C will still effectively have the privilege\&.

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.PP

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When a non\-owner of an object attempts to

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REVOKE

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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

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REVOKE ALL PRIVILEGES

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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\&.)

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.PP

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If a superuser chooses to issue a

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GRANT

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REVOKE

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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 might require use of

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CASCADE

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as stated above\&.

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.PP

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REVOKE

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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

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WITH GRANT OPTION

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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

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WITH GRANT OPTION\&. For example, if table

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is owned by role

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g1, of which role

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is a member, then

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can revoke privileges on

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that are recorded as being granted by

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g1\&. This would include grants made by

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as well as by other members of role

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g1\&.

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.PP

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If the role executing

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REVOKE

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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

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SET ROLE

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to become the specific role you want to do the

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REVOKE

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as\&. Failure to do so might lead to revoking privileges other than the ones you intended, or not revoking anything at all\&.

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.SH "EXAMPLES"

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.PP

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Revoke insert privilege for the public on table

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films:

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.sp

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.if n \{\

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.RS 4

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.\}

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.nf

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REVOKE INSERT ON films FROM PUBLIC;

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.fi

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.if n \{\

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.RE

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.\}

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.PP

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Revoke all privileges from user

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manuel

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on view

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kinds:

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.sp

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.if n \{\

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.RS 4

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.\}

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.nf

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REVOKE ALL PRIVILEGES ON kinds FROM manuel;

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.fi

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.if n \{\

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.RE

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.\}

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.sp

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Note that this actually means

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\(lqrevoke all privileges that I granted\(rq\&.

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.PP

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Revoke membership in role

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admins

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from user

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joe:

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.sp

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.if n \{\

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.RS 4

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.\}

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.nf

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REVOKE admins FROM joe;

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.fi

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.if n \{\

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.RE

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.\}

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.SH "COMPATIBILITY"

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.PP

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The compatibility notes of the

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\fBGRANT\fR(7)

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command apply analogously to

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REVOKE\&. The keyword

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RESTRICT

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CASCADE

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is required according to the standard, but

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PostgreSQL

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assumes

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RESTRICT

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by default\&.

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.SH "SEE ALSO"

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.sp

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\fBGRANT\fR(7)

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