Milan,

Would that statement not be equally slow if the column was plain ASCII? It would only be fast if you had
SUBSTRING(vc1 FROM 2000 FOR 6)
indexed, and in that case, using an indexed utf-8 column would also be fast.

--- In Firebird-Architect@yahoogroups.com, Milan Babuskov <milanb@...> wrote:
>
> Sergey Mereutsa wrote:
> > AWH> Why do you say UTF-8 is slow?
> >
> > Because you can not count string length, for example, without walking
> > it all - because each char in UTF8 (if we speak about it native
> > representation) can be from 1 to 6 bytes length.
>
> Admittedly, doing something like...
>
> select *
> from atable
> where SUBSTRING(vc1 FROM 2000 FOR 6) = 'Sergey'
>
> ...would be very slow. But how often do you really have to do stuff like
> this on the server?
>
> --
> Milan Babuskov