NAME

       SET_SESSION_AUTHORIZATION - set the session user identifier and the current user
       identifier of the current session

SYNOPSIS

       SET [ SESSION | LOCAL ] SESSION AUTHORIZATION user_name
       SET [ SESSION | LOCAL ] SESSION AUTHORIZATION DEFAULT
       RESET SESSION AUTHORIZATION

DESCRIPTION

       This command sets the session user identifier and the current user identifier of the
       current SQL session to be user_name. The user name can be written as either an identifier
       or a string literal. Using this command, it is possible, for example, to temporarily
       become an unprivileged user and later switch back to being a superuser.

       The session user identifier is initially set to be the (possibly authenticated) user name
       provided by the client. The current user identifier is normally equal to the session user
       identifier, but might change temporarily in the context of SECURITY DEFINER functions and
       similar mechanisms; it can also be changed by SET ROLE (SET_ROLE(7)). The current user
       identifier is relevant for permission checking.

       The session user identifier can be changed only if the initial session user (the
       authenticated user) had the superuser privilege. Otherwise, the command is accepted only
       if it specifies the authenticated user name.

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

       The DEFAULT and RESET forms reset the session and current user identifiers to be the
       originally authenticated user name. These forms can be executed by any user.

NOTES

       SET SESSION AUTHORIZATION cannot be used within a SECURITY DEFINER function.

EXAMPLES

           SELECT SESSION_USER, CURRENT_USER;

            session_user | current_user
           --------------+--------------
            peter        | peter

           SET SESSION AUTHORIZATION 'paul';

           SELECT SESSION_USER, CURRENT_USER;

            session_user | current_user
           --------------+--------------
            paul         | paul

COMPATIBILITY

       The SQL standard allows some other expressions to appear in place of the literal
       user_name, but these options are not important in practice.  PostgreSQL allows identifier
       syntax ("username"), which SQL does not. 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.

       The privileges necessary to execute this command are left implementation-defined by the
       standard.

SEE ALSO

       SET ROLE (SET_ROLE(7))