remote exchange (GATHER, SINGLE, [])
    final sortaggregate over (ss_customer_sk, ss_item_sk)
        local exchange (GATHER, SINGLE, [])
            partial sortaggregate over (ss_customer_sk, ss_item_sk)
                join (LEFT, PARTITIONED):
                    scan store_sales_customer_item
                    local exchange (GATHER, SINGLE, [])
                        remote exchange (REPARTITION, hive:buckets=1, hiveTypes=[bigint], ["sr_customer_sk"])
                            scan store_returns
