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