Calculating Count Distinct Using Vertical Unions

A query statement is received that specifies a count distinct. Thereafter, a data flow graph that comprises a plurality of nodes for executing the query is generated. The nodes provide aggregation operations, sorting of results on join attributes and vertically appending columns of count distinct results with intermediate results from at least one of the aggregation operations. Thereafter, execution of the query is initiated using the data flow graph. Related apparatus, systems, techniques and articles are also described.