--- In firebird-support@yahoogroups.com, "Leyne, Sean" <Sean@B...> wrote:

> I'll spare us all the intricacies of the nature of an index in MGA based
> database, but suffice it to say, that the index provides 'guidance' to
> the engine regarding the rows which should match the criteria. The
> engine must, however, read each data row to confirm the actual field
> value.

Hmm. Oracle does not scan the table, if all I request is index fields.
It returns the data directly from the index. Actually Oracle has taken
this further to allow "index organized tables" which will completely
reside in the index storage. Very handy for link tables which only
contain foreign keys to other tables.

Thomas