> Hi Apinot!
>
> Simply because the quickest way to access rows is to do it in natural
> order. Indexes are useful when most rows can be eliminated because
> they do not match the criterium, but if almost all records are to be
> returned, then NATURAL will be quicker than using the index. Likewise,
> if an almost unique index is used for a table within the plan, then
> additional use of other indexes on that table may slow down the
> execution of the query (the optimizer in Firebird 1.5 is smarter than
> the one in Firebird 1.0). A typical example would be if you already
> used an index on NAME, then using an additional index for COUNTRY
> ought to be avoided in most cases.
>
> Set