How to add uuid() to PostgreSQL?

Updated
UUID support is already in latest version of PostgreSQL. This is not longer needed.
http://www.postgresql.org/docs/8.3/static/datatype-uuid.html

What is uuid?

UUID stands for Universally Unique Identifier. The UUIDs generated can be reasonably expected to be unique within a system and unique across all systems. They could be used, for instance, to generate unique HTTP cookies across multiple web servers without communication between the servers, and without fear of a name clash.

I really don't like the MySQL uuid() implementation, so I have to create my own uuid() function using libuuid.

This is something similar to uuid() function I created for MySQL which works pretty well in PostgreSQL:

Source code for pguuid.c :
/*
(C) Claudiu RAVEICA

*/

#include <uuid/uuid.h>
#include <pgsql/server/postgres.h>
#include <pgsql/server/fmgr.h>
PG_FUNCTION_INFO_V1(uuid);

Datum
uuid()
{
struct varlena *p;
uuid_t uu;
uuid_generate(uu);
char buffer[37];
uuid_unparse(uu, buffer);
p = palloc(strlen(buffer) + VARHDRSZ);
p->vl_len = strlen(buffer) + VARHDRSZ;
memcpy(VARDATA(p), buffer,strlen(buffer));
PG_RETURN_TEXT_P(p);
}

gcc -fPIC -shared -O2 pguuid.c -luuid -o pguuid.so

Copy pguuid.so to your PostgreSQL lib directory (E.g.: /usr/lib/pgsql)

CREATE FUNCTION uuid() RETURNS text AS
'/usr/lib/pgsql/pguuid.so', 'uuid'
LANGUAGE C STRICT;
Examples:

SELECT UUID();
uuid
————————————–
0cd1954c-8555-4348-b425-afc5a7158ce4
(1 row)

Warning!

This works only on platforms that have libuuid.

Another similar project:

http://gborg.postgresql.org/project/pguuid/projdisplay.php