/**
 * Implements hook_field_storage_purge().
 */
function {{ machine_name }}_field_storage_purge($entity_type, $entity, $field, $instance) {
  list($id, $vid, $bundle) = entity_extract_ids($entity_type, $entity);

  $table_name = _field_sql_storage_tablename($field);
  $revision_name = _field_sql_storage_revision_tablename($field);
  db_delete($table_name)
    ->condition('entity_type', $entity_type)
    ->condition('entity_id', $id)
    ->execute();
  db_delete($revision_name)
    ->condition('entity_type', $entity_type)
    ->condition('entity_id', $id)
    ->execute();
}