The Post Revisions feature in WordPress takes up database space that I’d rather not waste. So I found out how to disable the feature. Add this to
// disable post revisions define('WP_POST_REVISIONS', false);
Then, clean up the database with this SQL:
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'