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<title>SET SESSION AUTHORIZATION</title>
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<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry" lang="en">
<a name="sql-set-session-authorization"></a><div class="titlepage"></div>
<div class="refnamediv">
<h2>Name</h2>
<p>SET SESSION AUTHORIZATION — set the session user identifier and the current user identifier of the current session</p>
</div>
<a name="id788353"></a><div class="refsynopsisdiv">
<h2>Synopsis</h2>
<pre class="synopsis">SET [ SESSION | LOCAL ] SESSION AUTHORIZATION <em class="replaceable"><code>username</code></em>
SET [ SESSION | LOCAL ] SESSION AUTHORIZATION DEFAULT
RESET SESSION AUTHORIZATION</pre>
</div>
<div class="refsect1" lang="en">
<a name="id788380"></a><h2>Description</h2>
<p> This command sets the session user identifier and the current user
identifier of the current SQL-session context to be <em class="replaceable"><code>username</code></em>. The user name may 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.
</p>
<p> 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
may change temporarily in the context of “<span class="quote">setuid</span>”
functions and similar mechanisms; it can also be changed by
<a href="sql-set-role.html">SET ROLE</a>.
The current user identifier is relevant for permission checking.
</p>
<p> The session user identifier may be changed only if the initial session
user (the <em class="firstterm">authenticated user</em>) had the
superuser privilege. Otherwise, the command is accepted only if it
specifies the authenticated user name.
</p>
<p> The <code class="literal">SESSION</code> and <code class="literal">LOCAL</code> modifiers act the same
as for the regular <a href="sql-set.html">SET</a>
command.
</p>
<p> The <code class="literal">DEFAULT</code> and <code class="literal">RESET</code> forms reset the session
and current user identifiers to be the originally authenticated user
name. These forms may be executed by any user.
</p>
</div>
<div class="refsect1" lang="en">
<a name="id788478"></a><h2>Examples</h2>
<pre class="programlisting">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</pre>
</div>
<div class="refsect1" lang="en">
<a name="id788491"></a><h2>Compatibility</h2>
<p> The SQL standard allows some other expressions to appear in place
of the literal <em class="replaceable"><code>username</code></em>, but these options
are not important in practice. <span class="productname">PostgreSQL</span>
allows identifier syntax (<code class="literal">"username"</code>), which SQL
does not. SQL does not allow this command during a transaction;
<span class="productname">PostgreSQL</span> does not make this
restriction because there is no reason to.
The <code class="literal">SESSION</code> and <code class="literal">LOCAL</code> modifiers are a
<span class="productname">PostgreSQL</span> extension, as is the
<code class="literal">RESET</code> syntax.
</p>
<p> The privileges necessary to execute this command are left
implementation-defined by the standard.
</p>
</div>
<div class="refsect1" lang="en">
<a name="id788559"></a><h2>See Also</h2>
<span class="simplelist"><a href="sql-set-role.html">SET ROLE</a></span>
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