If computed field type filtered into UDF, the lots of calculate can't make
a big time loose, (but blunt developer can make other horror, for examle
endless loop).
IB engine every time can recalculate fields for identical content.
I can't see real problems, and it much easy realize then expression index
(mentioned by Ann) and it don't violence to SQL standard or concept.

eMeL

> -----Original Message-----
> From: Nando Dessena [mailto:nandod@...]
>
> > I know, IB can't create index for a computed by column.
> > I see, but WHY CAN'T?
>
> because a computed column isn't stored and thus it cannot be indexed.
> It seems to me that you are proposing persistent computed fields, which
> would be a shortcut over what we have today (that is a real field with a
> couple of triggers to keep it in sync), just less flexible (now you can
> decide exactly under what conditions to recalculate a value in the
> update trigger, whereas a persistent computed field would be
> recalculated every time a record is written - unless the engine gets
> very very smart).
> Is there some other point I am missing?
> Ciao
> --
> ____
> _/\/ando
>