SELECT custkey, sum(totalprice)
FROM orders
GROUP BY custkey
ORDER BY 2 DESC

EXPLAIN

                                      Query Plan
---------------------------------------------------------------------------------------
 Fragment 0 [SINGLE]
     Output layout: [custkey, sum]
     Output partitioning: SINGLE []
     Stage Execution Strategy: UNGROUPED_EXECUTION
     Output[custkey, _col1]
     │   Layout: [custkey:bigint, sum:double]
     │   Estimates: {rows: ? (?), cpu: ?, memory: ?, network: ?}
     │   _col1 := sum
     └─ RemoteMerge[1]
            Layout: [custkey:bigint, sum:double]

 Fragment 1 [ROUND_ROBIN]
     Output layout: [custkey, sum]
     Output partitioning: SINGLE []
     Stage Execution Strategy: UNGROUPED_EXECUTION
     LocalMerge[sum DESC_NULLS_LAST]
     │   Layout: [custkey:bigint, sum:double]
     │   Estimates: {rows: ? (?), cpu: ?, memory: ?, network: ?}
     └─ PartialSort[sum DESC_NULLS_LAST]
        │   Layout: [custkey:bigint, sum:double]
        └─ RemoteSource[2]
               Layout: [custkey:bigint, sum:double]

 Fragment 2 [HASH]
     Output layout: [custkey, sum]
     Output partitioning: ROUND_ROBIN []
     Stage Execution Strategy: UNGROUPED_EXECUTION
     Aggregate(FINAL)[custkey]
     │   Layout: [custkey:bigint, sum:double]
     │   Estimates: {rows: ? (?), cpu: ?, memory: ?, network: ?}
     │   sum := sum("sum_0")
     └─ LocalExchange[HASH] ("custkey")
        │   Layout: [custkey:bigint, sum_0:row(bigint, boolean, double, boolean)]
        │   Estimates: {rows: ? (?), cpu: ?, memory: ?, network: ?}
        └─ RemoteSource[3]
               Layout: [custkey:bigint, sum_0:row(bigint, boolean, double, boolean)]

 Fragment 3 [tpch:orders:1500000]
     Output layout: [custkey, sum_0]
     Output partitioning: HASH [custkey]
     Stage Execution Strategy: UNGROUPED_EXECUTION
     Aggregate(PARTIAL)[custkey]
     │   Layout: [custkey:bigint, sum_0:row(bigint, boolean, double, boolean)]
     │   sum_0 := sum("totalprice")
     └─ TableScan[tpch:orders:sf1.0, grouped = false]
            Layout: [custkey:bigint, totalprice:double]
            Estimates: {rows: 1500000 (25.75MB), cpu: 25.75M, memory: 0B, network: 0B}
            custkey := tpch:custkey
            totalprice := tpch:totalprice
            tpch:orderstatus
                :: [[F], [O], [P]]

EXPLAIN ANALYZE

The output of EXPLAIN ANALYZE is missing Fragment 0, which includes the RemoteMerge operation

                                                                   Query Plan
------------------------------------------------------------------------------------------------------------------------------------------------
 Fragment 1 [ROUND_ROBIN]
     CPU: 103.33ms, Scheduled: 158.80ms, Input: 99996 rows (1.72MB); per task: avg.: 33332.00 std.dev.: 6899.92, Output: 99996 rows (1.72MB)
     Output layout: [custkey, sum]
     Output partitioning: SINGLE []
     Stage Execution Strategy: UNGROUPED_EXECUTION
     LocalMerge[sum DESC_NULLS_LAST]
     │   Layout: [custkey:bigint, sum:double]
     │   Estimates: {rows: ? (?), cpu: ?, memory: ?, network: ?}
     │   CPU: 46.00ms (1.00%), Scheduled: 71.00ms (1.15%), Output: 99996 rows (1.72MB)
     │   Input avg.: 8333.00 rows, Input std.dev.: 107.83%
     └─ PartialSort[sum DESC_NULLS_LAST]
        │   Layout: [custkey:bigint, sum:double]
        │   CPU: 55.00ms (1.19%), Scheduled: 80.00ms (1.30%), Output: 99996 rows (1.72MB)
        │   Input avg.: 8333.00 rows, Input std.dev.: 107.83%
        └─ RemoteSource[2]
               Layout: [custkey:bigint, sum:double]
               CPU: 1.00ms (0.02%), Scheduled: 5.00ms (0.08%), Output: 99996 rows (1.72MB)
               Input avg.: 8333.00 rows, Input std.dev.: 107.83%

 Fragment 2 [HASH]
     CPU: 262.03ms, Scheduled: 406.03ms, Input: 1203848 rows (41.33MB); per task: avg.: 401282.67 std.dev.: 623.89, Output: 99996 rows (1.72MB)
     Output layout: [custkey, sum]
     Output partitioning: ROUND_ROBIN []
     Stage Execution Strategy: UNGROUPED_EXECUTION
     Aggregate(FINAL)[custkey]
     │   Layout: [custkey:bigint, sum:double]
     │   Estimates: {rows: ? (?), cpu: ?, memory: ?, network: ?}
     │   CPU: 125.00ms (2.71%), Scheduled: 186.00ms (3.01%), Output: 99996 rows (1.72MB)
     │   Input avg.: 100320.67 rows, Input std.dev.: 1.19%
     │   Collisions avg.: 15354.34 (1066.97% est.), Collisions std.dev.: 141.49%
     │   sum := sum("sum_0")
     └─ LocalExchange[HASH] ("custkey")
        │   Layout: [custkey:bigint, sum_0:row(bigint, boolean, double, boolean)]
        │   Estimates: {rows: ? (?), cpu: ?, memory: ?, network: ?}
        │   CPU: 90.00ms (1.95%), Scheduled: 124.00ms (2.01%), Output: 1203848 rows (41.33MB)
        │   Input avg.: 100320.67 rows, Input std.dev.: 118.61%
        └─ RemoteSource[3]
               Layout: [custkey:bigint, sum_0:row(bigint, boolean, double, boolean)]
               CPU: 40.00ms (0.87%), Scheduled: 54.00ms (0.87%), Output: 1203848 rows (41.33MB)
               Input avg.: 100320.67 rows, Input std.dev.: 118.61%

 Fragment 3 [tpch:orders:1500000]
     CPU: 4.26s, Scheduled: 5.65s, Input: 1500000 rows (25.75MB); per task: avg.: 500000.00 std.dev.: 11.31, Output: 1203848 rows (41.33MB)
     Output layout: [custkey, sum_0]
     Output partitioning: HASH [custkey]
     Stage Execution Strategy: UNGROUPED_EXECUTION
     Aggregate(PARTIAL)[custkey]
     │   Layout: [custkey:bigint, sum_0:row(bigint, boolean, double, boolean)]
     │   CPU: 1.02s (22.06%), Scheduled: 1.53s (24.85%), Output: 1203848 rows (41.33MB)
     │   Input avg.: 41666.67 rows, Input std.dev.: 0.01%
     │   Collisions avg.: 25484.65 (105.71% est.), Collisions std.dev.: 141.47%
     │   sum_0 := sum("totalprice")
     └─ TableScan[tpch:orders:sf1.0, grouped = false]
            Layout: [custkey:bigint, totalprice:double]
            Estimates: {rows: 1500000 (25.75MB), cpu: 25.75M, memory: 0B, network: 0B}
            CPU: 3.24s (70.21%), Scheduled: 4.12s (66.73%), Output: 1500000 rows (25.75MB)
            Input avg.: 41666.67 rows, Input std.dev.: 0.01%
            custkey := tpch:custkey
            totalprice := tpch:totalprice
            tpch:orderstatus
                :: [[F], [O], [P]]