Roman Rokytskyy wrote:

>In my real-world, change of the database schema in the production database
>is never done on the fly.
>

In the web world of 24/7 availability, I can't take my database down for
more than the few milliseconds to restart a new server version. All
scheme upgrades must be done with the database running multi-user
production. I know that batch world was different, but we're not in
Kansas no more, baby. It can (and should) be done, but it takes
thought, planning, and care.