Ubuntu Manpage: GRANT - define access privileges

name
synopsis
description
notes
examples
compatibility
see also

Provided by: postgres-xc-client_1.1-2ubuntu2_amd64

NAME

       GRANT - define access privileges

SYNOPSIS

       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_name [, ...] )
           [, ...] | ALL [ PRIVILEGES ] ( column_name [, ...] ) }
           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 DOMAIN domain_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 { USAGE | ALL [ PRIVILEGES ] }
           ON TYPE type_name [, ...]
           TO { [ GROUP ] role_name | PUBLIC } [, ...] [ WITH GRANT OPTION ]

       GRANT role_name [, ...] TO role_name [, ...] [ WITH ADMIN OPTION ]

DESCRIPTION

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.

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.

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.

Postgres-XC grants default privileges on some types of objects to PUBLIC. No privileges are granted to
PUBLIC by default on tables, columns, schemas or tablespaces. For other types, the default privileges
granted to PUBLIC are as follows: CONNECT and CREATE TEMP TABLE for databases; EXECUTE privilege for
functions; and USAGE privilege for languages. The object owner can, of course, REVOKE both default and
expressly granted 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
(ALTER_DEFAULT_PRIVILEGES(7)) command.

The possible privileges are:

SELECT
Allows SELECT(7) from any column, or the specific columns listed, of the specified table, view, or
sequence. Also allows the use of COPY(7) TO. This privilege is also needed to reference existing
column values in UPDATE(7) or DELETE(7). For sequences, this privilege also allows the use of the
currval function. For large objects, this privilege allows the object to be read.

INSERT
Allows INSERT(7) 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(7) FROM.

UPDATE
Allows UPDATE(7) 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.

DELETE
Allows 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.)

TRUNCATE
Allows TRUNCATE(7) on the specified table.

REFERENCES
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.

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 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 types and domains, this privilege allow the use of the type or domain in the creation of tables,
functions, and other schema objects. (Note that it does not control general “usage” of the type, such
as values of the type appearing in queries. It only prevents objects from being created that depend
on the type. The main purpose of the privilege is controlling which users create dependencies on a
type, which could prevent the owner from changing the type later.)

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.

ALL PRIVILEGES
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.

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(7) 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(1)'s \dp command to obtain information about existing privileges for tables and columns. For
example:

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 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;
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.

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.

       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.

       According to the SQL standard, grant options can be granted to PUBLIC; Postgres-XC only supports granting
       grant options to roles.

       The SQL standard provides for a USAGE privilege on other kinds of objects: character sets, collations,
       translations.

       In the SQL standard, sequences only have a USAGE privilege, which controls the use of the NEXT VALUE FOR
       expression, which is equivalent to the function nextval in Postgres-XC. The sequence privileges SELECT
       and UPDATE are PostgreSQL extensions. The application of the sequence USAGE privilege to the currval
       function is also a PostgreSQL extension (as is the function itself).

       Privileges on databases, tablespaces, schemas, and languages are PostgreSQL extensions.