What you describe is what they describe as well: > For column-level changes, this often means adding new columns to a table that have the characteristics you w

What you describe is what they describe as well: > For column-level changes, this often means adding new columns to a table that have the characteristics you want while leaving the current columns as-is. I think what makes it confusing is that their diagrams depict a completely separate schema, but what they describe is really just altering the existing schema.