>> Is there any possibility to alter table by user who is not admin nor
> owner
>> of this table ?
>
> No.
> But then again you don't really want to try this when anyone else is
> connected either.

But, why ?
Many times I need to add some extra calculated fields or additional fields
to store additional informations. I need to do it when the first user with
new software connect to database. Only this new software can understand
changes. Changes are important for future use, but software will be upgraded
for all users in few days. Every user with new software can see changes and
can update database with new informations, others peoples works without
problems with old software.

Jacek