suse man page for set_role

SET 
ROLE(7)							   SQL Commands 						       SET ROLE(7)

NAME
       SET ROLE - set the current user identifier of the current session

SYNOPSIS
       SET [ SESSION | LOCAL ] ROLE rolename
       SET [ SESSION | LOCAL ] ROLE NONE
       RESET ROLE

DESCRIPTION
       This  command sets the current user identifier of the current SQL session to be rolename. The role name can be written as either an identi-
       fier or a string literal.  After SET ROLE, permissions checking for SQL commands is carried out as though the named role were the one  that
       had logged in originally.

       The  specified  rolename 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.)

       The SESSION and LOCAL modifiers act the same as for the regular SET [set(7)] command.

       The NONE and RESET forms reset the current user identifier to be the current session user identifier.  These forms can be executed  by  any
       user.

NOTES
       Using  this  command,  it  is  possible	to  either  add privileges or restrict one's privileges. If the session user role has the INHERITS
       attribute, then it automatically has all the privileges of every role that it could SET ROLE to; in this case 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 NOINHERITS attribute, SET ROLE drops the privileges	assigned  directly
       to the session user and instead acquires the privileges available to the named role.

       In particular, when a superuser chooses to SET ROLE to a non-superuser role, she loses her superuser privileges.

       SET  ROLE  has  effects comparable to SET SESSION AUTHORIZATION [set_session_authorization(7)], but the privilege checks involved are quite
       different. Also, SET SESSION AUTHORIZATION determines which roles are allowable for later SET ROLE commands, whereas  changing  roles  with
       SET ROLE does not change the set of roles allowed to a later SET ROLE.

       SET ROLE does not process session variables as specified by the role's ALTER ROLE [alter_role(7)] settings; this only happens during login.

       SET ROLE cannot be used within a SECURITY DEFINER function.

EXAMPLES
       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

COMPATIBILITY
       PostgreSQL allows identifier syntax ("rolename"), while the SQL standard requires the role name to be written as a string literal. SQL does
       not allow this command during a transaction; PostgreSQL does not make this restriction because there is no  reason  to.	 The  SESSION  and
       LOCAL modifiers are a PostgreSQL extension, as is the RESET syntax.

SEE ALSO
       SET SESSION AUTHORIZATION [set_session_authorization(7)]

SQL - Language Statements					    2010-05-14							       SET ROLE(7)