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<!--
doc/src/sgml/ref/set_role.sgml
PostgreSQL documentation
-->
<refentry id="SQL-SET-ROLE">
<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>
<indexterm zone="sql-set-role">
<primary>SET ROLE</primary>
</indexterm>
<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</>, permissions checking for SQL commands
is carried out as though the named role were the one that had logged
in originally.
</para>
<para>
The specified <replaceable class="parameter">role_name</replaceable>
must be a role that the current session user is a member of.
(If the session user is a superuser, any role can be selected.)
</para>
<para>
The <literal>SESSION</> and <literal>LOCAL</> modifiers act the same
as for the regular <xref linkend="SQL-SET">
command.
</para>
<para>
The <literal>NONE</> and <literal>RESET</> forms reset the current
user identifier to be 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 the <literal>INHERITS</>
attribute, then it automatically has all the privileges of every role that
it could <command>SET ROLE</> to; in this case <command>SET ROLE</>
effectively drops all the privileges assigned directly to the session user
and to the other roles it is a member of, leaving only the privileges
available to the named role. On the other hand, if the session user role
has the <literal>NOINHERITS</> attribute, <command>SET ROLE</> drops the
privileges assigned directly to the session user and instead acquires the
privileges available to the named role.
</para>
<para>
In particular, when a superuser chooses to <command>SET ROLE</> to a
non-superuser role, she loses her superuser privileges.
</para>
<para>
<command>SET ROLE</> has effects comparable to
<xref linkend="sql-set-session-authorization">, but the privilege
checks involved are quite different. Also,
<command>SET SESSION AUTHORIZATION</> determines which roles are
allowable for later <command>SET ROLE</> commands, whereas changing
roles with <command>SET ROLE</> does not change the set of roles
allowed to a later <command>SET ROLE</>.
</para>
<para>
<command>SET ROLE</> does not process session variables as specified by
the role's <xref linkend="sql-alterrole"> settings; this only happens during
login.
</para>
<para>
<command>SET ROLE</> cannot be used within a
<literal>SECURITY DEFINER</> 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>"rolename"</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</> and <literal>LOCAL</> modifiers are a
<productname>PostgreSQL</productname> extension, as is the
<literal>RESET</> syntax.
</para>
</refsect1>
<refsect1>
<title>See Also</title>
<simplelist type="inline">
<member><xref linkend="sql-set-session-authorization"></member>
</simplelist>
</refsect1>
</refentry>
|
