/**
 * Implements hook_field_update().
 */
function {{ machine_name }}_field_update($entity_type, $entity, $field, $instance, $langcode, &$items) {
  if (variable_get('taxonomy_maintain_index_table', TRUE) && $field['storage']['type'] == 'field_sql_storage' && $entity_type == 'node') {
    $first_call = &drupal_static(__FUNCTION__, array());

    // We don't maintain data for old revisions, so clear all previous values
    // from the table. Since this hook runs once per field, per object, make
    // sure we only wipe values once.
    if (!isset($first_call[$entity->nid])) {
      $first_call[$entity->nid] = FALSE;
      db_delete('taxonomy_index')->condition('nid', $entity->nid)->execute();
    }
    // Only save data to the table if the node is published.
    if ($entity->status) {
      $query = db_insert('taxonomy_index')->fields(array('nid', 'tid', 'sticky', 'created'));
      foreach ($items as $item) {
        $query->values(array(
          'nid' => $entity->nid,
          'tid' => $item['tid'],
          'sticky' => $entity->sticky,
          'created' => $entity->created,
        ));
      }
      $query->execute();
    }
  }
}