At 05:00 PM 3/6/2002 +0100, Nando Dessena wrote:

>László,
>
> > 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.

There is a think called an expression index which is used
in some PC databases. Most of the code exists in the
engine to create & manage them, from back in the bad old
days where we were trying for complete dBase emulation.

Indexing computed fields is more of a problem because computed
fields can be volatile. The examples that László gave could
be handled by expression indexes.


Regards,

Ann
www.ibphoenix.com
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