--- In firebird-support@yahoogroups.com, mat wrote:

> Hi all,
> I've got the following error during restore:
>
> gbak: ERROR: attempt to store duplicate value (visible to active
> transactions) in unique index "RDB$INDEX_2"
>
> How to find out which values are exacly duplicated??
> Gbak with -i switch also doesn't work.
> thanks in advance for any help

Try

SELECT UniqueField
FROM MyTable
GROUP BY UniqueField
HAVING COUNT(*) > 1

HTH,
Set