i have a custom search widget, that is searching only one custom post type that contain a meta_key that is greater than or equal to 1, in which i am gathering post_id. of all of those post_id(s), i am wanting to exclude those that have meta_key '_start_date' (stored like 01-16-2015) with value >= 'search_input_start_date' AND meta_key '_end_date' (stored like 01-16-2015) with value <= 'search_input_end_date'.
my question is: should I be using the action 'pre_get_posts' and the above as $args, or should I be using the filter 'posts_where' and directly going to the $wpdb ?