> > We can't read data from the index. It would be nice if we could, but we
> > can't. I think we believe that there are very few cases where this
> > would be win. Usually you need non-indexed data too.
>
> I have used other databases where this _is_ possible in the past, and
> the win is big when the programmer codes for it. Sure, most cases don't
> just use indexed data, but if the programmer knows that the database
> supports index-only scans then sometimes an extreme performance
> requirement can be met.
>
Yes, totally true. It is an extreme optimization. In Ingres, you could
actually SELECT on the index and use that when needed.
-- Bruce Momjian | http://www.op.net/~candle pgman@candle.pha.pa.us | (610)
853-3000+ If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill,
Pennsylvania19026
