[WordPress] Code from our blog post - Using WordPress Transients to Reduce Database Load http://www.limecanvas.com/using-wordpress-transients-reduce-database-load/

functions.php

global $wpdb;
$transient_name = 'lc-latest-10-posts';
$post_ids = get_transient( $transient_name );
if ( $post_ids == FALSE ){
	$sql = "SELECT post.ID
	FROM $wpdb->posts post
	WHERE
		post.post_type = 'post'
	AND post.post_status = 'publish'
	ORDER BY post.post_date
	DESC
	LIMIT 0,10";
	$results = $wpdb->get_col( $sql );
	if( $results ){
		foreach ( $results as $result ){
			$post_ids[] = $result;
		}
		set_transient( $transient_name, $post_ids, 60 * 60 * 6 );
	}
}