Re:

claus.pruefer@webcodex.de wrote:

> and a UNIQUE INDEX on columns "groupid,orderby"
>
> now i want to update
>
> UPDATE
> orderby SET orderby = orderby +10
> WHERE groupid = 1;
>
> -> FAILS because of UNIQUE INDEX

This is a Known Issue(tm).  (A "gotcha", some would say).

http://archives.postgresql.org/pgsql-sql/2004-10/msg00146.php
Surely you can find better references in the archives, but I'm too lazy.
(keywords: "deferrable unique constraint")

--
Alvaro Herrera                                http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.