At 12:16 AM 3/08/2004 +1000, Alan McDonald wrote:

> > b. Is there a way that you know, where an application can detect if
> > other users are logged into the database, to be sure that they can run any
> > utility scripts without logged in users getting in the way?
>
>if you are not using sysdba for all your connections, i.e. you use the
>security db for your users and not your own schema, then you can use the
>shutdown db method but this has it's own problems.

This is misleading. Shutdown doesn't have "its own problems", as long as
you can protect your users' sites from "rogue"
sysdbas. Carelessly-deployed installations have problems. Those who know
and use the sysdba login should be tightly restricted - *especially* if
you're deploying a database that is going to have hands-off metadata updates.

>If you are adding fields you don't have to worry at all.

Oh yes you do. If you add a non-nullable field or add one that alters an
integrity relationship, you have to be very careful. Non-nullable fields
should be defined with a default and set to that default as soon as the
metadata change is committed.

If you take the update route as recommended by Alan, it's not necessarily
going to be a piece of cake. If you take the build-anew route recommended
by Lester, with good data extraction and pumping tools, it will take longer
but you have plenty of fall-back and can also log the causes of
failures. But the dump-and-pump approach won't be practicable with very
large databases if you're doing it often.

People are using both approaches successfully.

/heLen