/**
 * Implements hook_field_storage_details().
 */
function {{ machine_name }}_field_storage_details($field) {
  $details = array();

  // Add field columns.
  foreach ((array) $field['columns'] as $column_name => $attributes) {
    $real_name = _field_sql_storage_columnname($field['field_name'], $column_name);
    $columns[$column_name] = $real_name;
  }
  return array(
    'sql' => array(
      FIELD_LOAD_CURRENT => array(
        _field_sql_storage_tablename($field) => $columns,
      ),
      FIELD_LOAD_REVISION => array(
        _field_sql_storage_revision_tablename($field) => $columns,
      ),
    ),
  );
}