[wp-hackers] Skip Main Query

[Andy Skelton]

> No I've noticed that WordPress still queries the posts from the start page. Is there a way to avoid that? Since I don't need the posts, I don't want to make that query.

Just replace wp::query_posts() with something more appropriate for
your situation. Easy. ;-)

This is how I made the Freshly Pressed feed on WordPress.com. It's a
multisite feed that gets blog_id and post_id from a table. It
populates $wp_the_query with all of the values necessary for a loop,
avoiding the standard core query, and switching blogs on each post.

This code is from the theme's functions.php. It could be written as a
plugin as well. There are probably some useless or erroneous lines. I
haven't planned on refining or packaging this, so consider this its
GPL distribution. :) If you decide to make an official plugin from
this, please add "andy" and "automattic" as contributors.

add_action('init', 'freshlypressed_init');

// Runs at end of init. Supplants global WP object.
function freshlypressed_init() {
        $GLOBALS['wp'] =& new freshlypressed_wp();

	add_action('the_post', 'freshlypressed_the_post', 10, 1);
        add_action('loop_end', 'freshlypressed_the_post', 10, 1);

	add_filter('get_lastpostmodified', 'freshlypressed_latest', 10001);
}

// This gets the latest date from the right place so feed 304s work
properly.
function freshlypressed_latest() {
	global $wpdb;
	return $wpdb->get_var("SELECT picked_on FROM botm_en ORDER BY
picked_on DESC LIMIT 1");
}

// This runs before every loop and after the last one. It switches to
the post's blog for each post in the loop.
function freshlypressed_the_post($post = null) {
        restore_current_blog();
        if ( is_object($post) && isset($post->blog_id) )
		switch_to_blog($post->blog_id);
}

class freshlypressed_wp extends wp {
        function query_posts() {
                global $wp_the_query, $wpdb;
                $this->build_query_string();
                // $wp_the_query->query($this->query_vars);

		// The whole point of overriding this method is to replace that
                // commented third line with our post-gathering code
(below).

		$wp_the_query->parse_query($this->query_vars);

		// Nothing but feeds here. And none of those "singular" comment
feeds. Just paged feeds.
                if ( !is_feed() || is_singular() ) {
                        wp_redirect('/feed/');
                        die;
                }

		if ( isset($this->query_vars['paged']) )
                        $page = max(intval($this->query_vars['paged']), 1);
                else
                        $page = 1;
                $start = 10 * ($page - 1);
                $blog_posts = $wpdb->get_results("SELECT
SQL_CALC_FOUND_ROWS blog_id, post_id FROM botm_en ORDER BY picked_on
DESC LIMIT $start, 10");

		$wp_the_query->found_posts = $wpdb->get_var("SELECT FOUND_ROWS()");
                $wp_the_query->max_num_pages =
ceil($wp_the_query->found_posts / 10);
                $wp_the_query->post_count = 10;

		foreach ( $blog_posts as $a ) {
                        $post =
sanitize_post(get_blog_post($a->blog_id, $a->post_id), 'raw');
                        $post->blog_id = $a->blog_id;
                        $wp_the_query->posts[] = $post;
                }

		$wp_the_query->post = $wp_the_query->posts[0];

		if ( is_home() ) {
                        $wp_the_query->is_home = null;
                        $wp_the_query->is_archive = true;
                }
        }
}