remote exchange (GATHER, SINGLE, [])
    local exchange (GATHER, UNKNOWN, [])
        remote exchange (REPARTITION, ROUND_ROBIN, [])
            final aggregation over (count)
                local exchange (GATHER, SINGLE, [])
                    remote exchange (REPARTITION, HASH, ["count"])
                        partial aggregation over (count)
                            final aggregation over (custkey)
                                local exchange (GATHER, SINGLE, [])
                                    partial aggregation over (custkey)
                                        join (LEFT, PARTITIONED):
                                            remote exchange (REPARTITION, HASH, ["custkey"])
                                                scan customer
                                            local exchange (GATHER, SINGLE, [])
                                                remote exchange (REPARTITION, HASH, ["custkey_0"])
                                                    scan orders
