Getting number of certain days-of-the-week (weekend) from interval in PostgreSQL

Question

Given 2 timestamps in postgres, how do you calculate the time difference without counting whole Saturdays and Sundays?

OR

How do you count the number of Satu

Answer 1

You might find this blogpost helpful: http://www.depesz.com/index.php/2007/12/27/how-many-1sts-of-any-month-were-sundays-since-1901-01-01/