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<title>GRANT</title>
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<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry" lang="en">
<a name="sql-grant"></a><div class="titlepage"></div>
<div class="refnamediv">
<h2>Name</h2>
<p>GRANT — define access privileges</p>
</div>
<a name="id775784"></a><div class="refsynopsisdiv">
<h2>Synopsis</h2>
<pre class="synopsis">GRANT { { SELECT | INSERT | UPDATE | DELETE | RULE | REFERENCES | TRIGGER }
[,...] | ALL [ PRIVILEGES ] }
ON [ TABLE ] <em class="replaceable"><code>tablename</code></em> [, ...]
TO { <em class="replaceable"><code>username</code></em> | GROUP <em class="replaceable"><code>groupname</code></em> | PUBLIC } [, ...] [ WITH GRANT OPTION ]
GRANT { { CREATE | TEMPORARY | TEMP } [,...] | ALL [ PRIVILEGES ] }
ON DATABASE <em class="replaceable"><code>dbname</code></em> [, ...]
TO { <em class="replaceable"><code>username</code></em> | GROUP <em class="replaceable"><code>groupname</code></em> | PUBLIC } [, ...] [ WITH GRANT OPTION ]
GRANT { EXECUTE | ALL [ PRIVILEGES ] }
ON FUNCTION <em class="replaceable"><code>funcname</code></em> ( [ [ <em class="replaceable"><code>argmode</code></em> ] [ <em class="replaceable"><code>argname</code></em> ] <em class="replaceable"><code>argtype</code></em> [, ...] ] ) [, ...]
TO { <em class="replaceable"><code>username</code></em> | GROUP <em class="replaceable"><code>groupname</code></em> | PUBLIC } [, ...] [ WITH GRANT OPTION ]
GRANT { USAGE | ALL [ PRIVILEGES ] }
ON LANGUAGE <em class="replaceable"><code>langname</code></em> [, ...]
TO { <em class="replaceable"><code>username</code></em> | GROUP <em class="replaceable"><code>groupname</code></em> | PUBLIC } [, ...] [ WITH GRANT OPTION ]
GRANT { { CREATE | USAGE } [,...] | ALL [ PRIVILEGES ] }
ON SCHEMA <em class="replaceable"><code>schemaname</code></em> [, ...]
TO { <em class="replaceable"><code>username</code></em> | GROUP <em class="replaceable"><code>groupname</code></em> | PUBLIC } [, ...] [ WITH GRANT OPTION ]
GRANT { CREATE | ALL [ PRIVILEGES ] }
ON TABLESPACE <em class="replaceable"><code>tablespacename</code></em> [, ...]
TO { <em class="replaceable"><code>username</code></em> | GROUP <em class="replaceable"><code>groupname</code></em> | PUBLIC } [, ...] [ WITH GRANT OPTION ]
GRANT <em class="replaceable"><code>role</code></em> [, ...]
TO { <em class="replaceable"><code>username</code></em> | GROUP <em class="replaceable"><code>groupname</code></em> | PUBLIC } [, ...] [ WITH ADMIN OPTION ]</pre>
</div>
<div class="refsect1" lang="en">
<a name="sql-grant-description"></a><h2>Description</h2>
<p> The <code class="command">GRANT</code> 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.
</p>
<p> As of <span class="productname">PostgreSQL</span> 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 <code class="literal">GROUP</code>
to identify whether a grantee is a user or a group. <code class="literal">GROUP</code>
is still allowed in the command, but it is a noise word.
</p>
<div class="refsect2" lang="en">
<a name="sql-grant-description-objects"></a><h3>GRANT on Database Objects</h3>
<p> This variant of the <code class="command">GRANT</code> command gives specific
privileges on a database object to
one or more roles. These privileges are added
to those already granted, if any.
</p>
<p> The key word <code class="literal">PUBLIC</code> indicates that the
privileges are to be granted to all roles, including those that may
be created later. <code class="literal">PUBLIC</code> may 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
<code class="literal">PUBLIC</code>.
</p>
<p> If <code class="literal">WITH GRANT OPTION</code> is specified, the recipient
of the privilege may in turn grant it to others. Without a grant
option, the recipient cannot do that. Grant options cannot be granted
to <code class="literal">PUBLIC</code>.
</p>
<p> 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 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.
</p>
<p> Depending on the type of object, the initial default privileges may
include granting some privileges to <code class="literal">PUBLIC</code>.
The default is no public access for tables, schemas, and tablespaces;
<code class="literal">TEMP</code> table creation privilege for databases;
<code class="literal">EXECUTE</code> privilege for functions; and
<code class="literal">USAGE</code> privilege for languages.
The object owner may of course revoke these privileges. (For maximum
security, issue the <code class="command">REVOKE</code> in the same transaction that
creates the object; then there is no window in which another user
may use the object.)
</p>
<p> The possible privileges are:
</p>
<div class="variablelist"><dl>
<dt><span class="term">SELECT</span></dt>
<dd><p> Allows <a href="sql-select.html">SELECT</a> from any column of the
specified table, view, or sequence. Also allows the use of
<a href="sql-copy.html">COPY</a> TO. For sequences, this
privilege also allows the use of the <code class="function">currval</code> function.
</p></dd>
<dt><span class="term">INSERT</span></dt>
<dd><p> Allows <a href="sql-insert.html">INSERT</a> of a new row into the
specified table. Also allows <a href="sql-copy.html">COPY</a> FROM.
</p></dd>
<dt><span class="term">UPDATE</span></dt>
<dd><p> Allows <a href="sql-update.html">UPDATE</a> of any
column of the specified table. <code class="literal">SELECT ... FOR UPDATE</code>
and <code class="literal">SELECT ... FOR SHARE</code>
also require this privilege (besides the
<code class="literal">SELECT</code> privilege). For sequences, this
privilege allows the use of the <code class="function">nextval</code> and
<code class="function">setval</code> functions.
</p></dd>
<dt><span class="term">DELETE</span></dt>
<dd><p> Allows <a href="sql-delete.html">DELETE</a> of a row from the
specified table.
</p></dd>
<dt><span class="term">RULE</span></dt>
<dd><p> Allows the creation of a rule on the table/view. (See the <a href="sql-createrule.html">CREATE RULE</a> statement.)
</p></dd>
<dt><span class="term">REFERENCES</span></dt>
<dd><p> To create a foreign key constraint, it is
necessary to have this privilege on both the referencing and
referenced tables.
</p></dd>
<dt><span class="term">TRIGGER</span></dt>
<dd><p> Allows the creation of a trigger on the specified table. (See the
<a href="sql-createtrigger.html">CREATE TRIGGER</a> statement.)
</p></dd>
<dt><span class="term">CREATE</span></dt>
<dd>
<p> For databases, allows new schemas to be created within the database.
</p>
<p> For schemas, allows new objects to be created within the schema.
To rename an existing object, you must own the object <span class="emphasis"><em>and</em></span>
have this privilege for the containing schema.
</p>
<p> For tablespaces, allows tables and indexes 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.)
</p>
</dd>
<dt>
<span xmlns="http://www.w3.org/TR/xhtml1/transitional" class="term">TEMPORARY</span><br xmlns="http://www.w3.org/TR/xhtml1/transitional"></br><span class="term">TEMP</span>
</dt>
<dd><p> Allows temporary tables to be created while using the database.
</p></dd>
<dt><span class="term">EXECUTE</span></dt>
<dd><p> 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.)
</p></dd>
<dt><span class="term">USAGE</span></dt>
<dd>
<p> 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.
</p>
<p> 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 “<span class="quote">look up</span>”
objects within the schema.
</p>
</dd>
<dt><span class="term">ALL PRIVILEGES</span></dt>
<dd><p> Grant all of the available privileges at once.
The <code class="literal">PRIVILEGES</code> key word is optional in
<span class="productname">PostgreSQL</span>, though it is required by
strict SQL.
</p></dd>
</dl></div>
<p>
The privileges required by other commands are listed on the
reference page of the respective command.
</p>
</div>
<div class="refsect2" lang="en">
<a name="sql-grant-description-roles"></a><h3>GRANT on Roles</h3>
<p> This variant of the <code class="command">GRANT</code> 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.
</p>
<p> If <code class="literal">WITH ADMIN OPTION</code> is specified, the member may
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 <code class="literal">CREATEROLE</code> privilege can grant or revoke
membership in any role that is not a superuser.
</p>
</div>
</div>
<div class="refsect1" lang="en">
<a name="sql-grant-notes"></a><h2>Notes</h2>
<p> The <a href="sql-revoke.html">REVOKE</a> command is used
to revoke access privileges.
</p>
<p> When a non-owner of an object attempts to <code class="command">GRANT</code> 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 <code class="command">GRANT ALL
PRIVILEGES</code> 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.)
</p>
<p> It should be noted that database superusers can access
all objects regardless of object privilege settings. This
is comparable to the rights of <code class="literal">root</code> in a Unix system.
As with <code class="literal">root</code>, it's unwise to operate as a superuser
except when absolutely necessary.
</p>
<p> If a superuser chooses to issue a <code class="command">GRANT</code> or <code class="command">REVOKE</code>
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.)
</p>
<p> <code class="command">GRANT</code> and <code class="command">REVOKE</code> 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
<code class="literal">WITH GRANT OPTION</code> 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
<code class="literal">WITH GRANT OPTION</code>. For example, if table
<code class="literal">t1</code> is owned by role <code class="literal">g1</code>, of which role
<code class="literal">u1</code> is a member, then <code class="literal">u1</code> can grant privileges
on <code class="literal">t1</code> to <code class="literal">u2</code>, but those privileges will appear
to have been granted directly by <code class="literal">g1</code>. Any other member
of role <code class="literal">g1</code> could revoke them later.
</p>
<p> If the role executing <code class="command">GRANT</code> 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 <code class="command">SET ROLE</code> to become the
specific role you want to do the <code class="command">GRANT</code> as.
</p>
<p> Currently, <span class="productname">PostgreSQL</span> 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.
</p>
<p> Use <a href="app-psql.html" title="psql"><span class="refentrytitle"><a name="app-psql-title"></a><span class="application">psql</span></span></a>'s <code class="command">\z</code> command
to obtain information about existing privileges, for example:
</p>
<pre class="programlisting">=> \z mytable
Access privileges for database "lusitania"
Schema | Name | Type | Access privileges
--------+---------+-------+------------------------------------------------------------
public | mytable | table | {miriam=arwdRxt/miriam,=r/miriam,"group todos=arw/miriam"}
(1 row)</pre>
<p>
The entries shown by <code class="command">\z</code> are interpreted thus:
</p>
<pre class="programlisting"> =xxxx -- privileges granted to PUBLIC
uname=xxxx -- privileges granted to a user
group gname=xxxx -- privileges granted to a group
r -- SELECT ("read")
w -- UPDATE ("write")
a -- INSERT ("append")
d -- DELETE
R -- RULE
x -- REFERENCES
t -- TRIGGER
X -- EXECUTE
U -- USAGE
C -- CREATE
T -- TEMPORARY
arwdRxt -- ALL PRIVILEGES (for tables)
* -- grant option for preceding privilege
/yyyy -- user who granted this privilege</pre>
<p>
The above example display would be seen by user <code class="literal">miriam</code> after
creating table <code class="literal">mytable</code> and doing
</p>
<pre class="programlisting">GRANT SELECT ON mytable TO PUBLIC;
GRANT SELECT, UPDATE, INSERT ON mytable TO GROUP todos;</pre>
<p>
</p>
<p> If the “<span class="quote">Access privileges</span>” 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 may include some privileges for <code class="literal">PUBLIC</code> depending on the
object type, as explained above. The first <code class="command">GRANT</code> or
<code class="command">REVOKE</code> on an object
will instantiate the default privileges (producing, for example,
<code class="literal">{miriam=arwdRxt/miriam}</code>) and then modify them per the
specified request.
</p>
<p> Notice that the owner's implicit grant options are not marked in the
access privileges display. A <code class="literal">*</code> will appear only when
grant options have been explicitly granted to someone.
</p>
</div>
<div class="refsect1" lang="en">
<a name="sql-grant-examples"></a><h2>Examples</h2>
<p> Grant insert privilege to all users on table <code class="literal">films</code>:
</p>
<pre class="programlisting">GRANT INSERT ON films TO PUBLIC;</pre>
<p>
</p>
<p> Grant all available privileges to user <code class="literal">manuel</code> on view
<code class="literal">kinds</code>:
</p>
<pre class="programlisting">GRANT ALL PRIVILEGES ON kinds TO manuel;</pre>
<p>
Note that while the above will indeed grant all privileges if executed by a
superuser or the owner of <code class="literal">kinds</code>, when executed by someone
else it will only grant those permissions for which the someone else has
grant options.
</p>
<p> Grant membership in role <code class="literal">admins</code> to user <code class="literal">joe</code>:
</p>
<pre class="programlisting">GRANT admins TO joe;</pre>
<p>
</p>
</div>
<div class="refsect1" lang="en">
<a name="sql-grant-compatibility"></a><h2>Compatibility</h2>
<p> According to the SQL standard, the <code class="literal">PRIVILEGES</code>
key word in <code class="literal">ALL PRIVILEGES</code> is required. The
SQL standard does not support setting the privileges on more than
one object per command.
</p>
<p> <span class="productname">PostgreSQL</span> 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 <span class="productname">PostgreSQL</span> 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 “<span class="quote">_SYSTEM</span>”. Not being
“<span class="quote">_SYSTEM</span>”, the owner cannot revoke these rights.
</p>
<p> The SQL standard allows setting privileges for individual columns
within a table:
</p>
<pre class="synopsis">GRANT <em class="replaceable"><code>privileges</code></em>
ON <em class="replaceable"><code>table</code></em> [ ( <em class="replaceable"><code>column</code></em> [, ...] ) ] [, ...]
TO { PUBLIC | <em class="replaceable"><code>username</code></em> [, ...] } [ WITH GRANT OPTION ]</pre>
<p>
</p>
<p> The SQL standard provides for a <code class="literal">USAGE</code> privilege
on other kinds of objects: character sets, collations,
translations, domains.
</p>
<p> The <code class="literal">RULE</code> privilege, and privileges on
databases, tablespaces, schemas, languages, and sequences are
<span class="productname">PostgreSQL</span> extensions.
</p>
</div>
<div class="refsect1" lang="en">
<a name="id777051"></a><h2>See Also</h2>
<p> <a href="sql-revoke.html">REVOKE</a>
</p>
</div>
</div></body>
</html>
|
