GRANT — define access privileges
GRANT { { SELECT | INSERT | UPDATE | DELETE | TRUNCATE | REFERENCES | TRIGGER }
[, ...] | ALL [ PRIVILEGES ] }
ON { [ TABLE ] table_name [, ...]
| ALL TABLES IN SCHEMA schema_name [, ...] }
TO role_specification [, ...] [ WITH GRANT OPTION ]
GRANT { { SELECT | INSERT | UPDATE | REFERENCES } ( column_name [, ...] )
[, ...] | ALL [ PRIVILEGES ] ( column_name [, ...] ) }
ON [ TABLE ] table_name [, ...]
TO role_specification [, ...] [ WITH GRANT OPTION ]
GRANT { { USAGE | SELECT | UPDATE }
[, ...] | ALL [ PRIVILEGES ] }
ON { SEQUENCE sequence_name [, ...]
| ALL SEQUENCES IN SCHEMA schema_name [, ...] }
TO role_specification [, ...] [ WITH GRANT OPTION ]
GRANT { { CREATE | CONNECT | TEMPORARY | TEMP } [, ...] | ALL [ PRIVILEGES ] }
ON DATABASE database_name [, ...]
TO role_specification [, ...] [ WITH GRANT OPTION ]
GRANT { USAGE | ALL [ PRIVILEGES ] }
ON DOMAIN domain_name [, ...]
TO role_specification [, ...] [ WITH GRANT OPTION ]
GRANT { USAGE | ALL [ PRIVILEGES ] }
ON FOREIGN DATA WRAPPER fdw_name [, ...]
TO role_specification [, ...] [ WITH GRANT OPTION ]
GRANT { USAGE | ALL [ PRIVILEGES ] }
ON FOREIGN SERVER server_name [, ...]
TO role_specification [, ...] [ WITH GRANT OPTION ]
GRANT { EXECUTE | ALL [ PRIVILEGES ] }
ON { FUNCTION function_name [ ( [ [ argmode ] [ arg_name ] arg_type [, ...] ] ) ] [, ...]
| ALL FUNCTIONS IN SCHEMA schema_name [, ...] }
TO role_specification [, ...] [ WITH GRANT OPTION ]
GRANT { USAGE | ALL [ PRIVILEGES ] }
ON LANGUAGE lang_name [, ...]
TO role_specification [, ...] [ WITH GRANT OPTION ]
GRANT { { SELECT | UPDATE } [, ...] | ALL [ PRIVILEGES ] }
ON LARGE OBJECT loid [, ...]
TO role_specification [, ...] [ WITH GRANT OPTION ]
GRANT { { CREATE | USAGE } [, ...] | ALL [ PRIVILEGES ] }
ON SCHEMA schema_name [, ...]
TO role_specification [, ...] [ WITH GRANT OPTION ]
GRANT { CREATE | ALL [ PRIVILEGES ] }
ON TABLESPACE tablespace_name [, ...]
TO role_specification [, ...] [ WITH GRANT OPTION ]
GRANT { USAGE | ALL [ PRIVILEGES ] }
ON TYPE type_name [, ...]
TO role_specification [, ...] [ WITH GRANT OPTION ]
where role_specification can be:
[ GROUP ] role_name
| PUBLIC
| CURRENT_USER
| SESSION_USER
GRANT role_name [, ...] TO role_name [, ...] [ WITH ADMIN OPTION ] 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.
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 their 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.
PostgreSQL grants default privileges on some types of objects to
PUBLIC. No privileges are granted to
PUBLIC by default on
tables,
table columns,
sequences,
foreign data wrappers,
foreign servers,
large objects,
schemas,
or tablespaces.
For other types of objects, the default privileges
granted to PUBLIC are as follows:
CONNECT and TEMPORARY (create
temporary tables) privileges for databases;
EXECUTE privilege for functions; and
USAGE privilege for languages and data types
(including domains).
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
command.
The possible privileges are:
SELECT Allows SELECT from
any column, or the specific columns listed, of the specified table,
view, or sequence.
Also allows the use of
COPY TO.
This privilege is also needed to reference existing column values in
UPDATE or
DELETE.
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 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 FROM.
UPDATE Allows UPDATE 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 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.)
TRUNCATEAllows TRUNCATE on the specified table.
REFERENCESAllows creation of a foreign key constraint referencing the specified table, or specified column(s) of the table. (See the CREATE TABLE statement.)
TRIGGERAllows the creation of a trigger on the specified table. (See the CREATE TRIGGER statement.)
CREATEFor databases, allows new schemas and publications 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).
TEMPORARYTEMPAllows temporary tables to be created while using the specified database.
EXECUTEAllows 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.)
USAGEFor 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 allows 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 allows creation of new servers using the foreign-data wrapper.
For servers, this privilege allows creation of foreign tables using the server. Grantees may also create, alter, or drop their own user mappings associated with that server.
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.
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. A role is not considered to hold WITH ADMIN
OPTION on itself, but it may grant or revoke membership in
itself from a database session where the session user matches the
role. 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.
The REVOKE 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 they hold 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 one 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's \dp command
to obtain information about existing privileges for tables and
columns. For example:
=> \dp mytable
Access privileges
Schema | Name | Type | Access privileges | Column access privileges
--------+---------+-------+-----------------------+--------------------------
public | mytable | table | miriam=arwdDxt/miriam | col1:
: =r/miriam : miriam_rw=rw/miriam
: admin=arw/miriam
(1 row)
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.
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;
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 their
own ordinary privileges: for example, a table owner can make the table
read-only to themselves by revoking their own INSERT,
UPDATE, DELETE, and TRUNCATE
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 themselves; therefore they
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; PostgreSQL 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 PostgreSQL. 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.