> Alan McDonald wrote:
> > and each of these 50+ servers are fully vacated of users?
>
> It is possible that someone is connected.
>
> However, IMHO the engine should not allow DDL that requires exclusive
> access to run when you don't have it. Just like Foreign key creation
> failed with Firebird 1.0 when there were other attachments.
>
> --
> Milan Babuskov

true but the original OP was doing an alter table - not null i.e. DDL then
issuing a DML update to all row values.
He wasn't specific about when commits were done nor clear on whether users
were live on the system (including his own numerous connections to admin the
DB) at the time of these operations.
Seems to me that a lot can happen with these possibilities. I like to do
this kind of alter with noone on the DB and I know I can commit everything
without there being open transactions on the values.
Alan