fix(frontend): add project after simple agg to avoid noop updates (#1…

…8292)
risingwavelabs · Aug 28, 2024 · c4875c2 · c4875c2
1 parent 612955d
commit c4875c2
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Showing 18 changed files with 220 additions and 210 deletions.
diff --git a/src/frontend/planner_test/tests/testdata/output/agg.yaml b/src/frontend/planner_test/tests/testdata/output/agg.yaml
diff --git a/src/frontend/planner_test/tests/testdata/output/append_only.yaml b/src/frontend/planner_test/tests/testdata/output/append_only.yaml
@@ -33,7 +33,7 @@
     select max(v1) as max_v1 from t1;
   stream_plan: |-
     StreamMaterialize { columns: [max_v1], stream_key: [], pk_columns: [], pk_conflict: NoCheck }
-    └─StreamProject { exprs: [max(max(t1.v1))] }
+    └─StreamProject { exprs: [max(max(t1.v1))], noop_update_hint: true }
       └─StreamSimpleAgg [append_only] { aggs: [max(max(t1.v1)), count] }
         └─StreamExchange { dist: Single }
           └─StreamStatelessSimpleAgg { aggs: [max(t1.v1)] }

diff --git a/src/frontend/planner_test/tests/testdata/output/bushy_join.yaml b/src/frontend/planner_test/tests/testdata/output/bushy_join.yaml
@@ -8,7 +8,7 @@
   sql: select count(*) from t t1 join t t2 on t1.id = t2.id join t t3 on t1.id = t3.id join t t4 on t1.id = t4.id join t t5 on t1.id = t5.id join t t6 on t1.id = t6.id join t t7 on t1.id = t7.id join t t8 on t1.id = t8.id;
   stream_plan: |-
     StreamMaterialize { columns: [count], stream_key: [], pk_columns: [], pk_conflict: NoCheck }
-    └─StreamProject { exprs: [sum0(count)] }
+    └─StreamProject { exprs: [sum0(count)], noop_update_hint: true }
       └─StreamSimpleAgg { aggs: [sum0(count), count] }
         └─StreamExchange { dist: Single }
           └─StreamStatelessSimpleAgg { aggs: [count] }

diff --git a/src/frontend/planner_test/tests/testdata/output/ch_benchmark.yaml b/src/frontend/planner_test/tests/testdata/output/ch_benchmark.yaml
@@ -869,7 +869,7 @@
             └─BatchScan { table: order_line, columns: [order_line.ol_amount, order_line.ol_delivery_d, order_line.ol_quantity], distribution: SomeShard }
   stream_plan: |-
     StreamMaterialize { columns: [revenue], stream_key: [], pk_columns: [], pk_conflict: NoCheck }
-    └─StreamProject { exprs: [sum(sum(order_line.ol_amount))] }
+    └─StreamProject { exprs: [sum(sum(order_line.ol_amount))], noop_update_hint: true }
       └─StreamSimpleAgg { aggs: [sum(sum(order_line.ol_amount)), count] }
         └─StreamExchange { dist: Single }
           └─StreamStatelessSimpleAgg { aggs: [sum(order_line.ol_amount)] }
@@ -880,7 +880,7 @@
     Fragment 0
     StreamMaterialize { columns: [revenue], stream_key: [], pk_columns: [], pk_conflict: NoCheck }
     ├── tables: [ Materialize: 4294967294 ]
-    └── StreamProject { exprs: [sum(sum(order_line.ol_amount))] }
+    └── StreamProject { exprs: [sum(sum(order_line.ol_amount))], noop_update_hint: true }
         └── StreamSimpleAgg { aggs: [sum(sum(order_line.ol_amount)), count] }
             ├── tables: [ SimpleAggState: 0 ]
             └── StreamExchange Single from 1
@@ -1940,7 +1940,7 @@
         │           └─StreamProject { exprs: [stock.s_i_id, stock.s_order_cnt, ((stock.s_w_id * stock.s_i_id) % 10000:Int32)::Int64 as $expr1, stock.s_w_id] }
         │             └─StreamTableScan { table: stock, columns: [stock.s_i_id, stock.s_w_id, stock.s_order_cnt], stream_scan_type: ArrangementBackfill, stream_key: [stock.s_w_id, stock.s_i_id], pk: [s_w_id, s_i_id], dist: UpstreamHashShard(stock.s_w_id, stock.s_i_id) }
         └─StreamExchange { dist: Broadcast }
-          └─StreamProject { exprs: [(sum(sum(stock.s_order_cnt))::Decimal * 0.005:Decimal) as $expr3] }
+          └─StreamProject { exprs: [(sum(sum(stock.s_order_cnt))::Decimal * 0.005:Decimal) as $expr3], noop_update_hint: true }
             └─StreamSimpleAgg { aggs: [sum(sum(stock.s_order_cnt)), count] }
               └─StreamExchange { dist: Single }
                 └─StreamStatelessSimpleAgg { aggs: [sum(stock.s_order_cnt)] }
@@ -2008,7 +2008,7 @@
         └── BatchPlanNode
 
     Fragment 7
-    StreamProject { exprs: [(sum(sum(stock.s_order_cnt))::Decimal * 0.005:Decimal) as $expr3] }
+    StreamProject { exprs: [(sum(sum(stock.s_order_cnt))::Decimal * 0.005:Decimal) as $expr3], noop_update_hint: true }
     └── StreamSimpleAgg { aggs: [sum(sum(stock.s_order_cnt)), count] } { tables: [ SimpleAggState: 14 ] }
         └── StreamExchange Single from 8
 
@@ -2265,7 +2265,7 @@
                     └─BatchScan { table: order_line, columns: [order_line.ol_i_id, order_line.ol_amount, order_line.ol_delivery_d], distribution: SomeShard }
   stream_plan: |-
     StreamMaterialize { columns: [promo_revenue], stream_key: [], pk_columns: [], pk_conflict: NoCheck }
-    └─StreamProject { exprs: [((100.00:Decimal * sum(sum($expr1))) / (1:Decimal + sum(sum(order_line.ol_amount)))) as $expr2] }
+    └─StreamProject { exprs: [((100.00:Decimal * sum(sum($expr1))) / (1:Decimal + sum(sum(order_line.ol_amount)))) as $expr2], noop_update_hint: true }
       └─StreamSimpleAgg { aggs: [sum(sum($expr1)), sum(sum(order_line.ol_amount)), count] }
         └─StreamExchange { dist: Single }
           └─StreamStatelessSimpleAgg { aggs: [sum($expr1), sum(order_line.ol_amount)] }
@@ -2279,11 +2279,9 @@
                   └─StreamTableScan { table: item, columns: [item.i_id, item.i_data], stream_scan_type: ArrangementBackfill, stream_key: [item.i_id], pk: [i_id], dist: UpstreamHashShard(item.i_id) }
   stream_dist_plan: |+
     Fragment 0
-    StreamMaterialize { columns: [promo_revenue], stream_key: [], pk_columns: [], pk_conflict: NoCheck }
-    ├── tables: [ Materialize: 4294967294 ]
-    └── StreamProject { exprs: [((100.00:Decimal * sum(sum($expr1))) / (1:Decimal + sum(sum(order_line.ol_amount)))) as $expr2] }
-        └── StreamSimpleAgg { aggs: [sum(sum($expr1)), sum(sum(order_line.ol_amount)), count] }
-            ├── tables: [ SimpleAggState: 0 ]
+    StreamMaterialize { columns: [promo_revenue], stream_key: [], pk_columns: [], pk_conflict: NoCheck } { tables: [ Materialize: 4294967294 ] }
+    └── StreamProject { exprs: [((100.00:Decimal * sum(sum($expr1))) / (1:Decimal + sum(sum(order_line.ol_amount)))) as $expr2], noop_update_hint: true }
+        └── StreamSimpleAgg { aggs: [sum(sum($expr1)), sum(sum(order_line.ol_amount)), count] } { tables: [ SimpleAggState: 0 ] }
             └── StreamExchange Single from 1
 
     Fragment 1
@@ -2358,7 +2356,7 @@
         │     └─StreamProject { exprs: [revenue1.total_revenue, revenue1.supplier_no::Int64 as $expr1, revenue1.supplier_no] }
         │       └─StreamTableScan { table: revenue1, columns: [revenue1.supplier_no, revenue1.total_revenue], stream_scan_type: ArrangementBackfill, stream_key: [revenue1.supplier_no], pk: [supplier_no], dist: UpstreamHashShard(revenue1.supplier_no) }
         └─StreamExchange { dist: HashShard(max(max(revenue1.total_revenue))) }
-          └─StreamProject { exprs: [max(max(revenue1.total_revenue))] }
+          └─StreamProject { exprs: [max(max(revenue1.total_revenue))], noop_update_hint: true }
             └─StreamSimpleAgg { aggs: [max(max(revenue1.total_revenue)), count] }
               └─StreamExchange { dist: Single }
                 └─StreamHashAgg { group_key: [_vnode], aggs: [max(revenue1.total_revenue), count] }
@@ -2396,7 +2394,7 @@
         └── BatchPlanNode
 
     Fragment 5
-    StreamProject { exprs: [max(max(revenue1.total_revenue))] }
+    StreamProject { exprs: [max(max(revenue1.total_revenue))], noop_update_hint: true }
     └── StreamSimpleAgg { aggs: [max(max(revenue1.total_revenue)), count] } { tables: [ SimpleAggState: 11, SimpleAggCall0: 10 ] }
         └── StreamExchange Single from 6
 
@@ -2628,7 +2626,7 @@
                     └─BatchScan { table: order_line, columns: [order_line.ol_i_id, order_line.ol_quantity], distribution: SomeShard }
   stream_plan: |-
     StreamMaterialize { columns: [avg_yearly], stream_key: [], pk_columns: [], pk_conflict: NoCheck }
-    └─StreamProject { exprs: [(sum(sum(order_line.ol_amount)) / 2.0:Decimal) as $expr3] }
+    └─StreamProject { exprs: [(sum(sum(order_line.ol_amount)) / 2.0:Decimal) as $expr3], noop_update_hint: true }
       └─StreamSimpleAgg { aggs: [sum(sum(order_line.ol_amount)), count] }
         └─StreamExchange { dist: Single }
           └─StreamStatelessSimpleAgg { aggs: [sum(order_line.ol_amount)] }
@@ -2651,9 +2649,8 @@
     Fragment 0
     StreamMaterialize { columns: [avg_yearly], stream_key: [], pk_columns: [], pk_conflict: NoCheck }
     ├── tables: [ Materialize: 4294967294 ]
-    └── StreamProject { exprs: [(sum(sum(order_line.ol_amount)) / 2.0:Decimal) as $expr3] }
-        └── StreamSimpleAgg { aggs: [sum(sum(order_line.ol_amount)), count] }
-            ├── tables: [ SimpleAggState: 0 ]
+    └── StreamProject { exprs: [(sum(sum(order_line.ol_amount)) / 2.0:Decimal) as $expr3], noop_update_hint: true }
+        └── StreamSimpleAgg { aggs: [sum(sum(order_line.ol_amount)), count] } { tables: [ SimpleAggState: 0 ] }
             └── StreamExchange Single from 1
 
     Fragment 1
@@ -2861,7 +2858,7 @@
                 └─BatchScan { table: order_line, columns: [order_line.ol_w_id, order_line.ol_i_id, order_line.ol_amount, order_line.ol_quantity], distribution: SomeShard }
   stream_plan: |-
     StreamMaterialize { columns: [revenue], stream_key: [], pk_columns: [], pk_conflict: NoCheck }
-    └─StreamProject { exprs: [sum(sum(order_line.ol_amount))] }
+    └─StreamProject { exprs: [sum(sum(order_line.ol_amount))], noop_update_hint: true }
       └─StreamSimpleAgg { aggs: [sum(sum(order_line.ol_amount)), count] }
         └─StreamExchange { dist: Single }
           └─StreamStatelessSimpleAgg { aggs: [sum(order_line.ol_amount)] }
@@ -2880,7 +2877,7 @@
     Fragment 0
     StreamMaterialize { columns: [revenue], stream_key: [], pk_columns: [], pk_conflict: NoCheck }
     ├── tables: [ Materialize: 4294967294 ]
-    └── StreamProject { exprs: [sum(sum(order_line.ol_amount))] }
+    └── StreamProject { exprs: [sum(sum(order_line.ol_amount))], noop_update_hint: true }
         └── StreamSimpleAgg { aggs: [sum(sum(order_line.ol_amount)), count] }
             ├── tables: [ SimpleAggState: 0 ]
             └── StreamExchange Single from 1
@@ -3410,7 +3407,7 @@
               │   └─StreamProject { exprs: [orders.o_c_id, orders.o_w_id, orders.o_d_id, orders.o_id] }
               │     └─StreamTableScan { table: orders, columns: [orders.o_d_id, orders.o_w_id, orders.o_c_id, orders.o_id], stream_scan_type: ArrangementBackfill, stream_key: [orders.o_w_id, orders.o_d_id, orders.o_id], pk: [o_w_id, o_d_id, o_id], dist: UpstreamHashShard(orders.o_w_id, orders.o_d_id, orders.o_id) }
               └─StreamExchange { dist: Broadcast }
-                └─StreamProject { exprs: [(sum(sum(customer.c_balance)) / sum0(count(customer.c_balance))::Decimal) as $expr1] }
+                └─StreamProject { exprs: [(sum(sum(customer.c_balance)) / sum0(count(customer.c_balance))::Decimal) as $expr1], noop_update_hint: true }
                   └─StreamSimpleAgg { aggs: [sum(sum(customer.c_balance)), sum0(count(customer.c_balance)), count] }
                     └─StreamExchange { dist: Single }
                       └─StreamStatelessSimpleAgg { aggs: [sum(customer.c_balance), count(customer.c_balance)] }

diff --git a/src/frontend/planner_test/tests/testdata/output/cse_expr.yaml b/src/frontend/planner_test/tests/testdata/output/cse_expr.yaml
@@ -74,7 +74,7 @@
     └─StreamProject { exprs: [Sqrt($expr5) as $expr6, Case((sum0(count(t.v)) <= 1:Int64), null:Decimal, Sqrt(($expr4 / (sum0(count(t.v)) - 1:Int64)::Decimal))) as $expr7, $expr5, Case((sum0(count(t.v)) <= 1:Int64), null:Decimal, ($expr4 / (sum0(count(t.v)) - 1:Int64)::Decimal)) as $expr8] }
       └─StreamProject { exprs: [sum(sum($expr1)), sum(sum(t.v)), sum0(count(t.v)), ($expr4 / $expr3) as $expr5, $expr4] }
         └─StreamProject { exprs: [sum(sum($expr1)), sum(sum(t.v)), sum0(count(t.v)), (sum(sum($expr1))::Decimal - (($expr2 * $expr2) / $expr3)) as $expr4, $expr3] }
-          └─StreamProject { exprs: [sum(sum($expr1)), sum(sum(t.v)), sum0(count(t.v)), sum(sum(t.v))::Decimal as $expr2, sum0(count(t.v))::Decimal as $expr3] }
+          └─StreamProject { exprs: [sum(sum($expr1)), sum(sum(t.v)), sum0(count(t.v)), sum(sum(t.v))::Decimal as $expr2, sum0(count(t.v))::Decimal as $expr3], noop_update_hint: true }
             └─StreamSimpleAgg { aggs: [sum(sum($expr1)), sum(sum(t.v)), sum0(count(t.v)), count] }
               └─StreamExchange { dist: Single }
                 └─StreamStatelessSimpleAgg { aggs: [sum($expr1), sum(t.v), count(t.v)] }

diff --git a/src/frontend/planner_test/tests/testdata/output/dynamic_filter.yaml b/src/frontend/planner_test/tests/testdata/output/dynamic_filter.yaml
@@ -18,7 +18,7 @@
     └─StreamDynamicFilter { predicate: (t1.v1 > max(max(t2.v2))), output: [t1.v1, t1._row_id] }
       ├─StreamTableScan { table: t1, columns: [t1.v1, t1._row_id], stream_scan_type: ArrangementBackfill, stream_key: [t1._row_id], pk: [_row_id], dist: UpstreamHashShard(t1._row_id) }
       └─StreamExchange { dist: Broadcast }
-        └─StreamProject { exprs: [max(max(t2.v2))] }
+        └─StreamProject { exprs: [max(max(t2.v2))], noop_update_hint: true }
           └─StreamSimpleAgg { aggs: [max(max(t2.v2)), count] }
             └─StreamExchange { dist: Single }
               └─StreamHashAgg { group_key: [_vnode], aggs: [max(t2.v2), count] }
@@ -77,7 +77,7 @@
         ├─StreamProject { exprs: [t1.v1, (t1.v1 + t1.v1) as $expr1, t1._row_id] }
         │ └─StreamTableScan { table: t1, columns: [t1.v1, t1._row_id], stream_scan_type: ArrangementBackfill, stream_key: [t1._row_id], pk: [_row_id], dist: UpstreamHashShard(t1._row_id) }
         └─StreamExchange { dist: Broadcast }
-          └─StreamProject { exprs: [max(max(t2.v2))] }
+          └─StreamProject { exprs: [max(max(t2.v2))], noop_update_hint: true }
             └─StreamSimpleAgg { aggs: [max(max(t2.v2)), count] }
               └─StreamExchange { dist: Single }
                 └─StreamHashAgg { group_key: [_vnode], aggs: [max(t2.v2), count] }
@@ -129,7 +129,7 @@
         ├─StreamExchange { dist: HashShard(t1.v1) }
         │ └─StreamTableScan { table: t1, columns: [t1.v1, t1._row_id], stream_scan_type: ArrangementBackfill, stream_key: [t1._row_id], pk: [_row_id], dist: UpstreamHashShard(t1._row_id) }
         └─StreamExchange { dist: HashShard(max(max(t2.v2))) }
-          └─StreamProject { exprs: [max(max(t2.v2))] }
+          └─StreamProject { exprs: [max(max(t2.v2))], noop_update_hint: true }
             └─StreamSimpleAgg { aggs: [max(max(t2.v2)), count] }
               └─StreamExchange { dist: Single }
                 └─StreamHashAgg { group_key: [_vnode], aggs: [max(t2.v2), count] }
@@ -153,7 +153,7 @@
         ├─StreamProject { exprs: [t1.v1, t1.v1::Int64 as $expr1, t1._row_id] }
         │ └─StreamTableScan { table: t1, columns: [t1.v1, t1._row_id], stream_scan_type: ArrangementBackfill, stream_key: [t1._row_id], pk: [_row_id], dist: UpstreamHashShard(t1._row_id) }
         └─StreamExchange { dist: Broadcast }
-          └─StreamProject { exprs: [max(max(t2.v2))] }
+          └─StreamProject { exprs: [max(max(t2.v2))], noop_update_hint: true }
             └─StreamSimpleAgg { aggs: [max(max(t2.v2)), count] }
               └─StreamExchange { dist: Single }
                 └─StreamHashAgg { group_key: [_vnode], aggs: [max(t2.v2), count] }
@@ -169,7 +169,7 @@
     └─StreamDynamicFilter { predicate: (t1.v1 > max(max(t2.v2))), output: [t1.v1, t1._row_id] }
       ├─StreamTableScan { table: t1, columns: [t1.v1, t1._row_id], stream_scan_type: ArrangementBackfill, stream_key: [t1._row_id], pk: [_row_id], dist: UpstreamHashShard(t1._row_id) }
       └─StreamExchange { dist: Broadcast }
-        └─StreamProject { exprs: [max(max(t2.v2))] }
+        └─StreamProject { exprs: [max(max(t2.v2))], noop_update_hint: true }
           └─StreamSimpleAgg { aggs: [max(max(t2.v2)), count] }
             └─StreamExchange { dist: Single }
               └─StreamHashAgg { group_key: [_vnode], aggs: [max(t2.v2), count] }
@@ -191,7 +191,7 @@
     └─StreamDynamicFilter { predicate: (t1.v1 > $expr1), output: [t1.v1, t1._row_id] }
       ├─StreamTableScan { table: t1, columns: [t1.v1, t1._row_id], stream_scan_type: ArrangementBackfill, stream_key: [t1._row_id], pk: [_row_id], dist: UpstreamHashShard(t1._row_id) }
       └─StreamExchange { dist: Broadcast }
-        └─StreamProject { exprs: [(2:Int32 * max(max(t2.v2))) as $expr1] }
+        └─StreamProject { exprs: [(2:Int32 * max(max(t2.v2))) as $expr1], noop_update_hint: true }
           └─StreamSimpleAgg { aggs: [max(max(t2.v2)), count] }
             └─StreamExchange { dist: Single }
               └─StreamHashAgg { group_key: [_vnode], aggs: [max(t2.v2), count] }
@@ -220,7 +220,7 @@
       │ ├─StreamTableScan { table: t1, columns: [t1.v1, t1._row_id], stream_scan_type: ArrangementBackfill, stream_key: [t1._row_id], pk: [_row_id], dist: UpstreamHashShard(t1._row_id) }
       │ └─StreamExchange { dist: Broadcast }
       │   └─StreamShare { id: 6 }
-      │     └─StreamProject { exprs: [max(max(t2.v2))] }
+      │     └─StreamProject { exprs: [max(max(t2.v2))], noop_update_hint: true }
       │       └─StreamSimpleAgg { aggs: [max(max(t2.v2)), count] }
       │         └─StreamExchange { dist: Single }
       │           └─StreamHashAgg { group_key: [_vnode], aggs: [max(t2.v2), count] }
@@ -229,7 +229,7 @@
       └─StreamExchange { dist: Broadcast }
         └─StreamProject { exprs: [(max(max(t2.v2)) + 5:Int32) as $expr1] }
           └─StreamShare { id: 6 }
-            └─StreamProject { exprs: [max(max(t2.v2))] }
+            └─StreamProject { exprs: [max(max(t2.v2))], noop_update_hint: true }
               └─StreamSimpleAgg { aggs: [max(max(t2.v2)), count] }
                 └─StreamExchange { dist: Single }
                   └─StreamHashAgg { group_key: [_vnode], aggs: [max(t2.v2), count] }

diff --git a/src/frontend/planner_test/tests/testdata/output/lateral_subquery.yaml b/src/frontend/planner_test/tests/testdata/output/lateral_subquery.yaml
@@ -180,7 +180,7 @@
     where path_val = t1.id;
   stream_plan: |-
     StreamMaterialize { columns: [array_agg], stream_key: [], pk_columns: [], pk_conflict: NoCheck }
-    └─StreamProject { exprs: [array_agg(t1.n order_by($expr1 ASC))] }
+    └─StreamProject { exprs: [array_agg(t1.n order_by($expr1 ASC))], noop_update_hint: true }
       └─StreamSimpleAgg { aggs: [array_agg(t1.n order_by($expr1 ASC)), count] }
         └─StreamExchange { dist: Single }
           └─StreamProject { exprs: [t1.n, (projected_row_id + 1:Int64) as $expr1, t1._row_id, t2.p, t2.p, t2.d, t2.d, projected_row_id, t1.id, t2._row_id] }

diff --git a/src/frontend/planner_test/tests/testdata/output/limit.yaml b/src/frontend/planner_test/tests/testdata/output/limit.yaml
@@ -131,7 +131,7 @@
   stream_plan: |-
     StreamMaterialize { columns: [count], stream_key: [], pk_columns: [], pk_conflict: NoCheck }
     └─StreamTopN { order: [sum0(count) ASC], limit: 1, offset: 0 }
-      └─StreamProject { exprs: [sum0(count)] }
+      └─StreamProject { exprs: [sum0(count)], noop_update_hint: true }
         └─StreamSimpleAgg { aggs: [sum0(count), count] }
           └─StreamExchange { dist: Single }
             └─StreamStatelessSimpleAgg { aggs: [count] }
@@ -154,7 +154,7 @@
   stream_plan: |-
     StreamMaterialize { columns: [count], stream_key: [], pk_columns: [], pk_conflict: NoCheck }
     └─StreamTopN { order: [sum0(count) ASC], limit: 1, offset: 0 }
-      └─StreamProject { exprs: [sum0(count)] }
+      └─StreamProject { exprs: [sum0(count)], noop_update_hint: true }
         └─StreamSimpleAgg { aggs: [sum0(count), count] }
           └─StreamExchange { dist: Single }
             └─StreamStatelessSimpleAgg { aggs: [count] }

diff --git a/src/frontend/planner_test/tests/testdata/output/mv_column_name.yaml b/src/frontend/planner_test/tests/testdata/output/mv_column_name.yaml
@@ -63,7 +63,7 @@
     select count(*), max(a) from t;
   stream_plan: |-
     StreamMaterialize { columns: [count, max], stream_key: [], pk_columns: [], pk_conflict: NoCheck }
-    └─StreamProject { exprs: [sum0(count), max(max(t.a))] }
+    └─StreamProject { exprs: [sum0(count), max(max(t.a))], noop_update_hint: true }
       └─StreamSimpleAgg { aggs: [sum0(count), max(max(t.a)), count] }
         └─StreamExchange { dist: Single }
           └─StreamHashAgg { group_key: [_vnode], aggs: [count, max(t.a)] }