<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >SET SESSION AUTHORIZATION</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK REV="MADE" HREF="mailto:pgsql-docs@postgresql.org"><LINK REL="HOME" TITLE="PostgreSQL 8.0.11 Documentation" HREF="index.html"><LINK REL="UP" TITLE="SQL Commands" HREF="sql-commands.html"><LINK REL="PREVIOUS" TITLE="SET CONSTRAINTS" HREF="sql-set-constraints.html"><LINK REL="NEXT" TITLE="SET TRANSACTION" HREF="sql-set-transaction.html"><LINK REL="STYLESHEET" TYPE="text/css" HREF="stylesheet.css"><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"><META NAME="creation" CONTENT="2007-02-02T03:57:22"></HEAD ><BODY CLASS="REFENTRY" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="5" ALIGN="center" VALIGN="bottom" >PostgreSQL 8.0.11 Documentation</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="sql-set-constraints.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="sql-set-constraints.html" >Fast Backward</A ></TD ><TD WIDTH="60%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="top" ><A HREF="sql-set-transaction.html" >Fast Forward</A ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="top" ><A HREF="sql-set-transaction.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="SQL-SET-SESSION-AUTHORIZATION" ></A >SET SESSION AUTHORIZATION</H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN45482" ></A ><H2 >Name</H2 >SET SESSION AUTHORIZATION -- set the session user identifier and the current user identifier of the current session</DIV ><A NAME="AEN45485" ></A ><DIV CLASS="REFSYNOPSISDIV" ><A NAME="AEN45487" ></A ><H2 >Synopsis</H2 ><PRE CLASS="SYNOPSIS" >SET [ SESSION | LOCAL ] SESSION AUTHORIZATION <TT CLASS="REPLACEABLE" ><I >username</I ></TT > SET [ SESSION | LOCAL ] SESSION AUTHORIZATION DEFAULT RESET SESSION AUTHORIZATION</PRE ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN45490" ></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 <TT CLASS="REPLACEABLE" ><I >username</I ></TT >. 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 become 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. 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 <I CLASS="FIRSTTERM" >authenticated user</I >) had the superuser privilege. Otherwise, the command is accepted only if it specifies the authenticated user name. </P ><P > The <TT CLASS="LITERAL" >SESSION</TT > and <TT CLASS="LITERAL" >LOCAL</TT > modifiers act the same as for the regular <A HREF="sql-set.html" ><I >SET</I ></A > command. </P ><P > The <TT CLASS="LITERAL" >DEFAULT</TT > and <TT CLASS="LITERAL" >RESET</TT > 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" ><A NAME="AEN45505" ></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" ><A NAME="AEN45508" ></A ><H2 >Compatibility</H2 ><P > The SQL standard allows some other expressions to appear in place of the literal <TT CLASS="REPLACEABLE" ><I >username</I ></TT > which are not important in practice. <SPAN CLASS="PRODUCTNAME" >PostgreSQL</SPAN > allows identifier syntax (<TT CLASS="LITERAL" >"username"</TT >), 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 privileges necessary to execute this command are left implementation-defined by the standard. </P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="sql-set-constraints.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="sql-set-transaction.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >SET CONSTRAINTS</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="sql-commands.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >SET TRANSACTION</TD ></TR ></TABLE ></DIV ></BODY ></HTML >