delete all post revisions and all associated meta , comments, attachments and taxonomies

gistfile1.php

<?php
add_action('wp_footer','cleanup_revisions');
function cleanup_revisions(){
  global $wpdb;
	$sql = "SELECT `ID`
			FROM ($wpdb->posts)
            WHERE `post_type` = 'revision'
			ORDER BY `ID` DESC";
	$results = $wpdb -> get_results($sql,'ARRAY_N');
	if($results){
		echo "<!--";
		$x = 0;
		foreach ($results as $key => $value) {
			wp_delete_post( $value['id']);
			$x++;
		}
		echo "deleted $x post revisions -->";
	}
}