Non-Overlaping date interval index

[Pailloncy Jean-Gerard <jg@xxxxxxxx>]

Hi,

I wonder how to have a sort of "uniq" index on date interval, such  
that there is no date interval overlaping in the table.

exemple:
create table test (start timestamp, end timestamp);
with the constraint: end > start

Cordialement,
Jean-Gérard Pailloncy