Everything about The National is over-the-top. The band’s compositions are heartbreakingly sad, and its lyrics are intensely personal. Live, frontman Matt Berninger stumbles across the stage wrecked with emotion, downs whiskey, and writhes on the ground, his husky, baritone voice brooding and aching. Such emotions will be on full display at the Greek Theatre (2001 Gayley Rd., Berkeley) this weekend. Alaskan psych-rock band Portugal. The Man will open the show.