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>32.4. Server-side Functions</A
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><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
>,
   <CODE
CLASS="FUNCTION"
>lo_create</CODE
>,
   <CODE
CLASS="FUNCTION"
>lo_unlink</CODE
>,
   <CODE
CLASS="FUNCTION"
>lo_import</CODE
>, and
   <CODE
CLASS="FUNCTION"
>lo_export</CODE
>.
   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_create(43213);   -- attempts to create large object with OID 43213

SELECT lo_unlink(173454);  -- deletes large object with OID 173454

INSERT INTO image (name, raster)
    VALUES ('beautiful image', lo_import('/etc/motd'));

INSERT INTO image (name, raster)  -- same as above, but specify OID to use
    VALUES ('beautiful image', lo_import('/etc/motd', 68583));

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 do not require superuser privilege.
  </P
><P
>    The functionality of <CODE
CLASS="FUNCTION"
>lo_read</CODE
> and
    <CODE
CLASS="FUNCTION"
>lo_write</CODE
> is also available via server-side calls,
    but the names of the server-side functions differ from the client side
    interfaces in that they do not contain underscores.  You must call
    these functions as <CODE
CLASS="FUNCTION"
>loread</CODE
> and <CODE
CLASS="FUNCTION"
>lowrite</CODE
>.
  </P
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