What's the most efficient way to select the last n rows in a table without changing the table's structure?

Question

What\'s the most efficient way to select the last n number of rows in a table using mySQL? The table contains millions of rows, and at any given time I don\'t know how large

Answer 1

You would probably also want to add a descending index (or whatever they're called in mysql) as well to make the select fast if it's something you're going to do often.