<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >Server-Side Functions</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="Large Objects" HREF="largeobjects.html"><LINK REL="PREVIOUS" TITLE="Client Interfaces" HREF="lo-interfaces.html"><LINK REL="NEXT" TITLE="Example Program" HREF="lo-examplesect.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="SECT1" ><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="lo-interfaces.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="largeobjects.html" >Fast Backward</A ></TD ><TD WIDTH="60%" ALIGN="center" VALIGN="bottom" >Chapter 28. Large Objects</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="top" ><A HREF="largeobjects.html" >Fast Forward</A ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="top" ><A HREF="lo-examplesect.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="LO-FUNCS" >28.4. Server-Side Functions</A ></H1 ><P > There are server-side functions callable from SQL that correspond to each of the client-side functions described above; indeed, for the most part the client-side functions are simply interfaces to the equivalent server-side functions. The ones that are actually useful to call via SQL commands are <CODE CLASS="FUNCTION" >lo_creat</CODE ><A NAME="AEN25100" ></A >, <CODE CLASS="FUNCTION" >lo_unlink</CODE ><A NAME="AEN25103" ></A >, <CODE CLASS="FUNCTION" >lo_import</CODE ><A NAME="AEN25106" ></A >, and <CODE CLASS="FUNCTION" >lo_export</CODE ><A NAME="AEN25109" ></A >. Here are examples of their use: </P><PRE CLASS="PROGRAMLISTING" >CREATE TABLE image ( name text, raster oid ); SELECT lo_creat(-1); -- returns OID of new, empty large object SELECT lo_unlink(173454); -- deletes large object with OID 173454 INSERT INTO image (name, raster) VALUES ('beautiful image', lo_import('/etc/motd')); SELECT lo_export(image.raster, '/tmp/motd') FROM image WHERE name = 'beautiful image';</PRE ><P> </P ><P > The server-side <CODE CLASS="FUNCTION" >lo_import</CODE > and <CODE CLASS="FUNCTION" >lo_export</CODE > functions behave considerably differently from their client-side analogs. These two functions read and write files in the server's file system, using the permissions of the database's owning user. Therefore, their use is restricted to superusers. In contrast, the client-side import and export functions read and write files in the client's file system, using the permissions of the client program. The client-side functions can be used by any <SPAN CLASS="PRODUCTNAME" >PostgreSQL</SPAN > user. </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="lo-interfaces.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="lo-examplesect.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >Client Interfaces</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="largeobjects.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >Example Program</TD ></TR ></TABLE ></DIV ></BODY ></HTML >