def index_cols(db, table, index):

    '''Can also use this for UNIQUE constraints, because a UNIQUE index is

    automatically created. When you don't know whether something is a UNIQUE

    constraint or a UNIQUE index, use this function.'''

    check_name(table)

    check_name(index)

    module = util.root_module(db)

    if module == 'psycopg2':

        return list(values(run_query(db, '''\

SELECT attname

FROM pg_index

JOIN pg_class index ON index.oid = indexrelid

JOIN pg_class table_ ON table_.oid = indrelid

JOIN pg_attribute ON attrelid = indrelid AND attnum = ANY (indkey)

WHERE

    table_.relname = %(table)s

    AND index.relname = %(index)s

ORDER BY attnum

''',

            {'table': table, 'index': index})))

    else: raise NotImplementedError("Can't list index columns for "+module+

        ' database')