When you run knex migrations to add/modify table(s) with knex(using knex migrate:latest), it runs as a batch if
there's more than one file in the migrations directory, and more than one uncompleted migration files.
For example, if we have abc.js, def.js and ghi.js uncompleted migration files in the migrations directory.
knex migrate:latest runs all 3 in a single batch. migrate:rollback undo the last batch job(all 3 files) while
knex migrate:down undo ghi.js as the last file in the batch. Another knex migrate:down undo def.js and so on.