grant.sgml 12.00 KiB
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$Header: /cvsroot/pgsql/doc/src/sgml/ref/grant.sgml,v 1.23 2002/04/22 19:17:40 tgl Exp $
PostgreSQL documentation
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<refentry id="SQL-GRANT">
<refmeta>
<refentrytitle id="sql-grant-title">GRANT</refentrytitle>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>GRANT</refname>
<refpurpose>define access privileges</refpurpose>
</refnamediv>
<refsynopsisdiv>
<synopsis>
GRANT { { SELECT | INSERT | UPDATE | DELETE | RULE | REFERENCES | TRIGGER }
[,...] | ALL [ PRIVILEGES ] }
ON [ TABLE ] <replaceable class="PARAMETER">tablename</replaceable> [, ...]
TO { <replaceable class="PARAMETER">username</replaceable> | GROUP <replaceable class="PARAMETER">groupname</replaceable> | PUBLIC } [, ...]
GRANT { { CREATE | TEMPORARY | TEMP } [,...] | ALL [ PRIVILEGES ] }
ON DATABASE <replaceable>dbname</replaceable> [, ...]
TO { <replaceable class="PARAMETER">username</replaceable> | GROUP <replaceable class="PARAMETER">groupname</replaceable> | PUBLIC } [, ...]
GRANT { EXECUTE | ALL [ PRIVILEGES ] }
ON FUNCTION <replaceable>funcname</replaceable> ([<replaceable>type</replaceable>, ...]) [, ...]
TO { <replaceable class="PARAMETER">username</replaceable> | GROUP <replaceable class="PARAMETER">groupname</replaceable> | PUBLIC } [, ...]
GRANT { USAGE | ALL [ PRIVILEGES ] }
ON LANGUAGE <replaceable>langname</replaceable> [, ...]
TO { <replaceable class="PARAMETER">username</replaceable> | GROUP <replaceable class="PARAMETER">groupname</replaceable> | PUBLIC } [, ...]
GRANT { { CREATE | USAGE } [,...] | ALL [ PRIVILEGES ] }
ON SCHEMA <replaceable>schemaname</replaceable> [, ...]
TO { <replaceable class="PARAMETER">username</replaceable> | GROUP <replaceable class="PARAMETER">groupname</replaceable> | PUBLIC } [, ...]
</synopsis>
</refsynopsisdiv>
<refsect1 id="sql-grant-description">
<title>Description</title>
<para>
The <command>GRANT</command> command gives specific permissions on
an object (table, view, sequence, database, function, procedural language,
or schema) to
one or more users or groups of users. These permissions are added
to those already granted, if any.
</para>
<para>
The key word <literal>PUBLIC</literal> indicates that the
privileges are to be granted to all users, including those that may
be created later. <literal>PUBLIC</literal> may be thought of as an
implicitly defined group that always includes all users.
Note that any particular user will have the sum
of privileges granted directly to him, privileges granted to any group he
is presently a member of, and privileges granted to
<literal>PUBLIC</literal>.
</para>
<para>
Users other than the creator of an object do not have any access privileges
to the object unless the creator grants permissions.
There is no need to grant privileges to the creator of an object,
as the creator automatically holds all privileges.
(The creator could, however, choose to revoke
some of his own privileges for safety. Note that the ability to grant and revoke privileges is inherent in the creator and cannot
be lost. The right to drop the object is likewise inherent in the
creator, and cannot be granted or revoked.)
</para>
<para>
The possible privileges are:
<variablelist>
<varlistentry>
<term>SELECT</term>
<listitem>
<para>
Allows <xref linkend="sql-select" endterm="sql-select-title"> from any column of the
specified table, view, or sequence. Also allows the use of
<xref linkend="sql-copy" endterm="sql-copy-title"> FROM.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>INSERT</term>
<listitem>
<para>
Allows <xref linkend="sql-insert" endterm="sql-insert-title"> of a new row into the
specified table. Also allows <xref linkend="sql-copy" endterm="sql-copy-title"> TO.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>UPDATE</term>
<listitem>
<para>
Allows <xref linkend="sql-update" endterm="sql-update-title"> of any column of the
specified table. <literal>SELECT ... FOR UPDATE</literal>
also requires this privilege (besides the
<literal>SELECT</literal> privilege). For sequences, this
privilege allows the use of <function>nextval</function>,
<function>currval</function> and <function>setval</function>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>DELETE</term>
<listitem>
<para>
Allows <xref linkend="sql-delete" endterm="sql-delete-title"> of a row from the
specified table.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>RULE</term>
<listitem>
<para>
Allows the creation of a rule on the table/view. (See <xref
linkend="sql-createrule" endterm="sql-createrule-title"> statement.)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>REFERENCES</term>
<listitem>
<para>
To create a table with a foreign key constraint, it is
necessary to have this privilege on the table with the referenced key.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>TRIGGER</term>
<listitem>
<para>
Allows the creation of a trigger on the specified table. (See
<xref linkend="sql-createtrigger" endterm="sql-createtrigger-title"> statement.)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>CREATE</term>
<listitem>
<para>
For databases, allows new schemas to be created within the database.
</para>
<para>
For schemas, allows new objects to be created within the schema.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>TEMPORARY</term>
<term>TEMP</term>
<listitem>
<para>
Allows temporary tables to be created while using the database.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>EXECUTE</term>
<listitem>
<para>
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.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>USAGE</term>
<listitem>
<para>
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.
</para>
<para>
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 <quote>look up</>
objects within the schema.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>ALL PRIVILEGES</term>
<listitem>
<para>
Grant all of the privileges applicable to the object at once. The <literal>PRIVILEGES</literal> key word is optional in
<productname>PostgreSQL</productname>, though it is required by
strict SQL.
</para>
</listitem>
</varlistentry>
</variablelist>
The privileges required by other commands are listed on the
reference page of the respective command.
</para>
</refsect1>
<refsect1 id="SQL-GRANT-notes">
<title>Notes</title>
<para>
The <xref linkend="sql-revoke" endterm="sql-revoke-title"> command is used
to revoke access privileges.
</para>
<para>
It should be noted that database <firstterm>superusers</> can access
all objects regardless of object privilege settings. This
is comparable to the rights of <literal>root</> in a Unix system.
As with <literal>root</>, it's unwise to operate as a superuser
except when absolutely necessary.
</para>
<para>
Currently, to grant privileges in <productname>PostgreSQL</productname>
to only a few columns, you must
create a view having the desired columns and then grant privileges
to that view.
</para>
<para>
Use <xref linkend="app-psql">'s <command>\z</command> command
to obtain information about existing privileges, for example:
<programlisting>
lusitania=> \z mytable
Access privileges for database "lusitania"
Table | Access privileges
---------+---------------------------------------
mytable | {=r,miriam=arwdRxt,"group todos=arw"}
</programlisting>
The entries shown by <command>\z</command> are interpreted thus:
<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)
</programlisting>
The above example display would be seen by user <literal>miriam</> after
creating table <literal>mytable</> and doing
<programlisting>
GRANT SELECT ON mytable TO PUBLIC;
GRANT SELECT,UPDATE,INSERT ON mytable TO GROUP todos;
</programlisting>
</para>
<para>
If the <quote>Access privileges</> column is empty for a given object,
it means the object has default privileges (that is, its privileges field
is NULL). Currently, default privileges are interpreted the same way
for all object types: all privileges for the owner and no privileges for
anyone else. The first <command>GRANT</> on an object will instantiate
this default (producing, for example, <literal>{=,miriam=arwdRxt}</>)
and then modify it per the specified request.
</para>
</refsect1>
<refsect1 id="sql-grant-examples">
<title>Examples</title>
<para>
Grant insert privilege to all users on table films:
<programlisting>
GRANT INSERT ON films TO PUBLIC;
</programlisting>
</para>
<para>
Grant all privileges to user <literal>manuel</literal> on view <literal>kinds</literal>:
<programlisting>
GRANT ALL PRIVILEGES ON kinds TO manuel;
</programlisting>
</para>
</refsect1>
<refsect1 id="sql-grant-compatibility">
<title>Compatibility</title>
<refsect2>
<title>SQL92</title>
<para>
The <literal>PRIVILEGES</literal> key word in <literal>ALL
PRIVILEGES</literal> is required. <acronym>SQL</acronym> does not
support setting the privileges on more than one table per command.
</para>
<para>
The <acronym>SQL92</acronym> syntax for GRANT allows setting
privileges for individual columns within a table, and allows
setting a privilege to grant the same privileges to others:
<synopsis>
GRANT <replaceable class="PARAMETER">privilege</replaceable> [, ...]
ON <replaceable class="PARAMETER">object</replaceable> [ ( <replaceable class="PARAMETER">column</replaceable> [, ...] ) ] [, ...]
TO { PUBLIC | <replaceable class="PARAMETER">username</replaceable> [, ...] } [ WITH GRANT OPTION ]
</synopsis>
</para>
<para>
<acronym>SQL</acronym> allows to grant the USAGE privilege on
other kinds of objects: CHARACTER SET, COLLATION, TRANSLATION, DOMAIN.
</para>
<para>
The TRIGGER privilege was introduced in SQL99. The RULE privilege
is a PostgreSQL extension.
</para> </refsect2>
</refsect1>
<refsect1>
<title>See Also</title>
<simpara>
<xref linkend="sql-revoke">
</simpara>
</refsect1>
</refentry>
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