def extend_columns(self, column_data, kind):
<EOL>try:<EOL><INDENT>column_data = [self.escaped_names(d, '<STR_LIT:">') for d in column_data]<EOL><DEDENT>except Exception:<EOL><INDENT>column_data = []<EOL><DEDENT>metadata = self.dbmetadata[kind]<EOL>for relname, column in column_data:<EOL><INDENT>metadata[self.dbname][relname].append(column)<EOL>self.all_completions.add(column)<EOL><DEDENT>
Extend column metadata
        :param column_data: list of (rel_name, column_name) tuples
        :param kind: either 'tables' or 'views'
        :return: