atus column as index.
	 *
	 * @return bool
	 */
	private function make_error_code_column_index() {
		$error_code_column_exists = $this->column_exists( 'error_code' );
		if ( ! $error_code_column_exists ) {
			return $this->is_success( false );
		}

		if ( $this->index_exists( 'error_code_index' ) ) {
			return $this->is_success( true );
		}

		$index_added = $this->get_db()->query( "ALTER TABLE {$this->table_name} ADD INDEX `error_code_index` (`error_code`) " );
		return $this->is_success( $index_added );
	}
}