I am porting a BDE application to FB using using D3 and IBO v. 3.6.Dj .

The application is full of SetRangeStart..SetRangeEnd..ApplyRange
statements and (for the moment) I'd like not to change them into SQL
queries because I have very little time.

So understanding the exact working of this statement is important for me.

I thought that - using a full fledged database like FB - it was no more
needed to specify which index to activate.

After all, if a table know which indexes exist on it, it is no big effort
to come out with the most convenient index to use for a given range.

Alas! This seems only partly true.

Actually IBOTables don't seem able to automatically use externally defined
indexes.

If I try to set a table range on the fields of an external index (and I
don't specify IndexName:=AnExternalIndexName) I get the error message
"field is not indexed".

Could somebody explain me why ?

Thank you

Duilio