--- In firebird-support@yahoogroups.com, "Mohammad Jeffry"
<linuxlah@...> wrote:

>
> I understand that duplicate index can slow down firebird. What is

duplicate

> index? How can one create duplicate index? example please

Two different indices that reference the same field(s).

create index a on c(d);
create index b on c(d);

Normally it is less obvious. People may not realise that unique
constraints, foreign keys and primary keys automatically create an
index on those fields, and by defining their own index on those fields
they are creating a duplicate index.

Adam