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<!--
doc/src/sgml/ref/set_role.sgml
PostgreSQL documentation
-->
<refentry id="sql-set-role">
<indexterm zone="sql-set-role">
<primary>SET ROLE</primary>
</indexterm>
<refmeta>
<refentrytitle>SET ROLE</refentrytitle>
<manvolnum>7</manvolnum>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>SET ROLE</refname>
<refpurpose>set the current user identifier of the current session</refpurpose>
</refnamediv>
<refsynopsisdiv>
<synopsis>
SET [ SESSION | LOCAL ] ROLE <replaceable class="parameter">role_name</replaceable>
SET [ SESSION | LOCAL ] ROLE NONE
RESET ROLE
</synopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
This command sets the current user
identifier of the current SQL session to be <replaceable
class="parameter">role_name</replaceable>. The role name can be
written as either an identifier or a string literal.
After <command>SET ROLE</command>, permissions checking for SQL commands
is carried out as though the named role were the one that had logged
in originally.
</para>
<para>
The current session user must have the <literal>SET</literal> option for the
specified <replaceable class="parameter">role_name</replaceable>, either
directly or indirectly via a chain of memberships with the
<literal>SET</literal> option.
(If the session user is a superuser, any role can be selected.)
</para>
<para>
The <literal>SESSION</literal> and <literal>LOCAL</literal> modifiers act the same
as for the regular <link linkend="sql-set"><command>SET</command></link>
command.
</para>
<para>
<literal>SET ROLE NONE</literal> sets the current user identifier to the
current session user identifier, as returned by
<function>session_user</function>. <literal>RESET ROLE</literal> sets the
current user identifier to the connection-time setting specified by the
<link linkend="libpq-connect-options">command-line options</link>,
<link linkend="sql-alterrole"><command>ALTER ROLE</command></link>, or
<link linkend="sql-alterdatabase"><command>ALTER DATABASE</command></link>,
if any such settings exist. Otherwise, <literal>RESET ROLE</literal> sets
the current user identifier to the current session user identifier. These
forms can be executed by any user.
</para>
</refsect1>
<refsect1>
<title>Notes</title>
<para>
Using this command, it is possible to either add privileges or restrict
one's privileges. If the session user role has been granted memberships
<literal>WITH INHERIT TRUE</literal>, it automatically has all the
privileges of every such role. In this case, <command>SET ROLE</command>
effectively drops all the privileges except for those which the target role
directly possesses or inherits. On the other hand, if the session user role
has been granted memberships <literal>WITH INHERIT FALSE</literal>, the
privileges of the granted roles can't be accessed by default. However, if
the role was granted <literal>WITH SET TRUE</literal>, the
session user can use <command>SET ROLE</command> to drop the privileges
assigned directly to the session user and instead acquire the privileges
available to the named role. If the role was granted <literal>WITH INHERIT
FALSE, SET FALSE</literal> then the privileges of that role cannot be
exercised either with or without <literal>SET ROLE</literal>.
</para>
<para>
Note that when a superuser chooses to <command>SET ROLE</command> to a
non-superuser role, they lose their superuser privileges.
</para>
<para>
<command>SET ROLE</command> has effects comparable to
<link linkend="sql-set-session-authorization"><command>SET SESSION AUTHORIZATION</command></link>, but the privilege
checks involved are quite different. Also,
<command>SET SESSION AUTHORIZATION</command> determines which roles are
allowable for later <command>SET ROLE</command> commands, whereas changing
roles with <command>SET ROLE</command> does not change the set of roles
allowed to a later <command>SET ROLE</command>.
</para>
<para>
<command>SET ROLE</command> does not process session variables as specified by
the role's <link linkend="sql-alterrole"><command>ALTER ROLE</command></link> settings; this only happens during
login.
</para>
<para>
<command>SET ROLE</command> cannot be used within a
<literal>SECURITY DEFINER</literal> function.
</para>
</refsect1>
<refsect1>
<title>Examples</title>
<programlisting>
SELECT SESSION_USER, CURRENT_USER;
session_user | current_user
--------------+--------------
peter | peter
SET ROLE 'paul';
SELECT SESSION_USER, CURRENT_USER;
session_user | current_user
--------------+--------------
peter | paul
</programlisting>
</refsect1>
<refsect1>
<title>Compatibility</title>
<para>
<productname>PostgreSQL</productname>
allows identifier syntax (<literal>"<replaceable>rolename</replaceable>"</literal>), while
the SQL standard requires the role name to be written as a string
literal. SQL does not allow this command during a transaction;
<productname>PostgreSQL</productname> does not make this
restriction because there is no reason to.
The <literal>SESSION</literal> and <literal>LOCAL</literal> modifiers are a
<productname>PostgreSQL</productname> extension, as is the
<literal>RESET</literal> syntax.
</para>
</refsect1>
<refsect1>
<title>See Also</title>
<simplelist type="inline">
<member><xref linkend="sql-set-session-authorization"/></member>
</simplelist>
</refsect1>
</refentry>
|
