Ticket #18286: cf-guid-fix.php

<?php

/*
Plugin Name: CF GUID Fix 
Plugin URI: http://crowdfavorite.com/wordpress/plugins/cf-guid-fix/ 
Description: Correct duplicate GUID values created with versions of WordPress that exhibited a <a href="http://core.trac.wordpress.org/ticket/15041">non-unique GUID bug</a>.
Version: 1.0 
Author: Crowd Favorite
Author URI: http://crowdfavorite.com
*/

function cf_guid_fix_admin_init() {
        if (isset($_GET['cf_action'])) {
                switch ($_GET['cf_action']) {
                        case 'guid-fix':
                                cf_guid_fix();
                                wp_die('Post GUIDs should be unique now.');
                        break;
                }
        }
}
add_action('admin_init', 'cf_guid_fix_admin_init');

function cf_guid_fix() {
        global $wpdb;

// add index on GUID column
        $wpdb->query("
                ALTER TABLE $wpdb->posts
                ADD INDEX (guid)
        ");

// find non-unique GUID values

// NOTE: not including revisions since that's a whole other mess to 
// try to get the numbering right if we change the GUID

// this gets the GUIDs
//              SELECT guid
//              FROM $wpdb->posts
//              WHERE post_type != 'revision'
//              GROUP BY guid
//              HAVING COUNT(guid) > 1

// WORKS - but is very slow
//              SELECT ID
//              FROM $wpdb->posts
//              WHERE guid IN (
//                      SELECT guid
//                      FROM $wpdb->posts
//                      WHERE post_type != 'revision'
//                      GROUP BY guid
//                      HAVING COUNT(guid) > 1
//              )
//              AND post_type != 'revision'

        $non_unique_guids = $wpdb->get_col($wpdb->prepare("
                SELECT p1.ID
                FROM $wpdb->posts p1
                WHERE 1 < (
                        SELECT COUNT(ID) 
                        FROM $wpdb->posts p2 
                        WHERE p1.post_type != 'revision'
                        AND p1.guid = p2.guid
                )
                AND p1.post_type != 'revision'
        "));

// make them unique

        if (count($non_unique_guids)) {
                foreach ($non_unique_guids as $post_id) {
                        $url = site_url('?p='.$post_id);
                        $wpdb->query($wpdb->prepare("
                                UPDATE $wpdb->posts
                                SET guid = %s
                                WHERE ID = %d
                        ", $url, $post_id));
                }
        }

// remove index from GUID column
        $wpdb->query("
                ALTER TABLE $wpdb->posts
                DROP INDEX guid
        ");

}