Roblox Corporation
Computing cross products using map reduce

Abstract:

A request is received to generate cross products from a dataset based on a join field. The join field indicates that each of the cross products is to be generated from a corresponding subset of the dataset where the subset associated with identical keys. Responsive to receiving the request to generate the plurality of cross products of the dataset based on the join field, a set of map reduce jobs is performed on the dataset to generate the cross products. Performing the set of map reduce jobs generates groups of key-value pairs from the corresponding subsets of the dataset. Each key-value pair of a respective group of key-value pairs includes the identical keys. Responsive to performing the set of map reduce jobs, final output data is received that identifies the cross products for each of the groups of key-value pairs.