SET SESSION AUTHORIZATION

SET SESSION AUTHORIZATION

7

SQL - Language Statements

SET SESSION AUTHORIZATION

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

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`](#sql-set-role). 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`](#sql-set) 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
========
