Counting posts with argument without retrieving the posts

Question

Here’s one thing you could do. Create a WP_Query object but only include ids:

$args = array(
    'posts_per_page'    => -1,
    'post_type'         => 'books',
    's'                 => $s,
    'fields'            => 'ids',
);

$query          = new WP_Query( $args );
$post_counts    = $query->post_count;
wp_reset_postdata();

By using fields => ids you’re only returning the IDs. Also, WP_Query already does a count and supplies it as a property: post_count. Finally, since we are using a WP_Query we need to reset the globals with wp_reset_postdata().