1. A method for use in a multi-node database system, comprising: storing a plurality of built-in aggregate functions, including an aggregate function for calculating a percentage; receiving a database query that specifies the aggregate function for calculating a percentage; in response to the database query specifying the aggregate function, calculating the percentage; generating a result table having plural rows in response to the database query, wherein calculating the percentage comprises calculating plural percentage values for storing in corresponding rows of the result table; and wherein receiving the database query comprises receiving a database query having a group-by clause specifying grouping attributes defining plural first groups, each of the rows of the result table corresponding to respective first groups.