Proper syntax for a windowing function

Hi, all. I'm trying to figure out the proper syntax for queries such as a moving average over a window in MonetDB.

THis works:

sql>select avg(energy) from TABLENAME; +--------------------------+ | L3 | +==========================+ | 658.5049567388747 | +--------------------------+

This fails:

select avg(energy) OVER () from TABLENAME; SELECT: function 'avg' not found

(Welcome to mclient, the MonetDB/SQL interactive terminal (Jul2017-SP1) Database: MonetDB v11.27.5 (Jul2017-SP1), 'mapi:monetdb://SERVER2:50000/scada' )

How do I write such a query?

Many thanks.