Update model from within a command

[CundyTech]

I have a cmd that performs a database insert operation, row by row. I'd like to render the progress of that cmd in a progress bar. So my initial idea is to update the model from within the cmd, but obviously the view is only updated once the cmd returns a message upon completion.

Most examples of using progress bars just use a tick to update each second. How is a real world implementation achieved? Any hints or nudges in the right direction would be appreciated.