> i have a problem with my 27Gb FB2.5 Database. Doing a backup is workíng fine. Doing a restore is failing due to the following error:
>
> gbak: ERROR:attempt to store duplicate value (visible to active transactions) in
> unique index "RDB$INDEX_20"
> gbak:Exiting before completion due to errors
>
> Here`s the clue: The database is working fine. There are no duplicated roles, no duplicated datasets, index-reorg is working fine, gfix could`t find ANY errors.
>
> I tried to find out, which relation "RDB$INDEX_20" has. It refers to a table named "Abrechnung", Column named "RUECKBUCHUNG". But there are no duplicated values. In fact, Column "RUECKBUCHUNG" is always empty (IS NULL).
>
> Any Ideas?

IMHO, RDB$INDEX_20 is an index on the RDB$COLLATIONS system table. This
can be proved by:

select
i.rdb$relation_name
, s.rdb$field_name
from
rdb$indices i join rdb$index_segments s on (i.rdb$index_name =
s.rdb$index_name)
where
i.rdb$index_name = 'RDB$INDEX_20'


So, basically this means, there are duplicate values in
RDB$COLLATIONS.RDB$COLLATION_NAME. What do you get by executing the
following query?

select
rdb$collation_name
from
rdb$collations
group by
rdb$collation_name
having
count(*) > 1


Greetings from Austria (lost 1:2 unlucky). ;-)

Regards,
Thomas