1. A method implemented at least in part by a computer, the method comprising: for a plurality of database table partitions of a partitioned database table partitioned according to one or more partition columns of the partitioned database table, assigning the database table partitions to respective different nodes for a window calculation specified by a window operator comprising one or more specified partition columns that are the same as or a superset of the partition columns of the partitioned database table; via the database table partitions, calculating window function sub-results locally at the different nodes; and combining the local window function sub-results into an overall window function result of the window operator.