cross join:
    final aggregation over ()
        local exchange (GATHER, SINGLE, [])
            remote exchange (GATHER, SINGLE, [])
                partial aggregation over ()
                    join (INNER, REPLICATED):
                        join (INNER, REPLICATED):
                            join (INNER, REPLICATED):
                                scan web_sales
                                local exchange (GATHER, SINGLE, [])
                                    remote exchange (REPLICATE, BROADCAST, [])
                                        scan web_page
                            local exchange (GATHER, SINGLE, [])
                                remote exchange (REPLICATE, BROADCAST, [])
                                    scan time_dim
                        local exchange (GATHER, SINGLE, [])
                            remote exchange (REPLICATE, BROADCAST, [])
                                scan household_demographics
    final aggregation over ()
        local exchange (GATHER, SINGLE, [])
            remote exchange (GATHER, SINGLE, [])
                partial aggregation over ()
                    join (INNER, REPLICATED):
                        join (INNER, REPLICATED):
                            join (INNER, REPLICATED):
                                scan web_sales
                                local exchange (GATHER, SINGLE, [])
                                    remote exchange (REPLICATE, BROADCAST, [])
                                        scan web_page
                            local exchange (GATHER, SINGLE, [])
                                remote exchange (REPLICATE, BROADCAST, [])
                                    scan time_dim
                        local exchange (GATHER, SINGLE, [])
                            remote exchange (REPLICATE, BROADCAST, [])
                                scan household_demographics
