Partitioned Windows Sample Clauses

Partitioned Windows. The following CQL query expresses “Take the 10 most recent auctions from each seller and return the seller of the most expensive item.": SELECT A. seller , MAX (P. cost ) FROM Auctions [ PARTITION BY A. seller ROWS 10] AS A, Purchases AS P WHERE A. auction_id = P. auction_id GROUP BY ▇. ▇▇▇▇▇▇ ; The partitioned window operator expects a stream S and a positive number of tuple attributes in the window as an integer N. It splits the stream S into sub-streams such that the given attributes are unique for each stream. A tuple based window of size N is then applied on each sub-stream to create a number of continuously updated sub-relations. Finally, a relation R (the query output) is formed by taking the union of all sub-relations.