Raul,

> > index in two or three (non unique) slices, and then enforce uniqueness
> > by means of a trigger or two.
> > This has some disadvantages, too.
>
> In fact, the disadvantage is that the uniqueness can not be enforced with
> triggers !

This sentence is almost as incomplete as mine. ;-)
Actually, uniqueness cannot be enforced with triggers in a multi-user
environment. Otherwise it can be.
Now that's what I call a disadvantage ;-P.

> IB has a stupid low (about 200-300 bytes - I don't know for sure
> but is documented) limit for an index size.

It depends on the number of segments, on the data type of each segment
and on the character set for text fields, AFAIK.
Approx. 240 bytes in the questioner's case.
Ciao
--
____
_/\/ando