Postgres has something called updatable views so INSERTs, UPDATEs, DELETEs can be made against views just as if they were actual tables. For the example in the post, they work differently depending on if the insert is made against the new or old schema:

- For old schema (i.e. full_name is set): full_name is split in two, the first part is assigned to first_name and the second to last_name. This is controlled by the "up" setting in the migration.

- For new schema (i.e. first_name and last_name is set): full_name is set to first_name and last_name concatenated with a space. This is controlled by the "down" setting in the migration.