DELETE a,b,c FROM wp_posts a LEFT JOIN wp_term_relationships b ON (a.ID = b.object_id) LEFT JOIN wp_postmeta c ON (a.ID = c.post_id) WHERE a.post_type = 'revision'
Site Wide Limiting of Revisions in wp-config.php:
define('WP_POST_REVISIONS', false); //or if you want 1 revision: define('WP_POST_REVISIONS', 1);
note that you cannot delete all inherits in the wp_post status because each attachment inherits it’s short codes from the published article. If I publish id 271, then have 3 attachments, they’ll be numbered 272, 273, 274