A simple `vacuum` increments the `.dbinfo` "file change counter:" by one when from a logical point of view nothing really changed. My question is what types of changes are considered file changes? Is every successful `insert`, `update`, `delete` a file change? Is a change counted for each row affected or the whole transaction is a single change? When does the number reach a limit (32-bit)? Does it then wrap around to zero or stop counting? What is a practical use of this number?