I tried the four queries on a table that has 36k rows, using as parameter the amount of rows returned by the count(*) query, the fourth option is not accurate at all, actually it displays about 400k rows (this table have no modifications at all), and compared to the count(*) one, it less efficient as well.

The only one that gave the most reliable result and was fast, was the count(*) option, followed by the third query. That's what I've find for this table, it might change for bigger tables 🙂