gistfile1.php

<?php
/**
 * Get random posts; an alternate approach for dealing with large tables.
 *
 * MySQL queries that use ORDER BY RAND() can be pretty challenging and slow on large datasets.
 * This function is an alternative method for getting random posts, though it's still very very inefficent.
 * You probably don't want to use this function.
 *
 * Override the $vip_get_random_post_ids_where_add global to add your own WHERE condition:
 * $vip_get_random_post_ids_where_add = "AND post_status='publish' AND post_type='post' AND post_date_gmt > '2009-01-01 00:00:00';
 * 
 * You'll want to enable caching and avoid querying all posts by adding the following action:
 * add_action( 'save_post', 'vip_refresh_random_posts_all_ids', 1 ); // add this to functions.php
 *
 * @author tottdev
 * @param int $amount Optional. Amount of random posts to get. Default 1.
 * @param bool $return_ids Optional. To just get the IDs, set this to true, otherwise post objects are returned (the default).
 * @return array
 */