Choose cheapest aggregated path as base for chunk-wise aggregation

tsl/src/nodes/vector_agg/plan.c

@@ -409,6 +409,10 @@ has_vector_agg_node(Plan *plan, bool *has_normal_agg)
 	{
 		append_plans = castNode(Append, plan)->appendplans;
 	}
+	if (IsA(plan, MergeAppend))
+	{
+		append_plans = castNode(MergeAppend, plan)->mergeplans;
+	}
 	else if (IsA(plan, CustomScan))
 	{
 		custom = castNode(CustomScan, plan);
@@ -471,6 +475,10 @@ try_insert_vector_agg_node(Plan *plan)
 	{
 		append_plans = castNode(Append, plan)->appendplans;
 	}
+	else if (IsA(plan, MergeAppend))
+	{
+		append_plans = castNode(MergeAppend, plan)->mergeplans;
+	}
 	else if (IsA(plan, CustomScan))
 	{
 		CustomScan *custom = castNode(CustomScan, plan);

tsl/test/expected/cagg_union_view-14.out

@@ -355,31 +355,29 @@ SELECT _timescaledb_functions.cagg_watermark(:boundary_view_id);
 
 -- first UNION child should have no rows because no materialization has happened yet and 2nd child should have 4 rows
 :PREFIX SELECT * FROM boundary_view;
-                                                              QUERY PLAN                                                               
----------------------------------------------------------------------------------------------------------------------------------------
+                                                           QUERY PLAN                                                            
+---------------------------------------------------------------------------------------------------------------------------------
  Finalize GroupAggregate (actual rows=4 loops=1)
    Group Key: (time_bucket(10, _hyper_5_5_chunk."time"))
-   ->  Sort (actual rows=4 loops=1)
+   ->  Merge Append (actual rows=4 loops=1)
          Sort Key: (time_bucket(10, _hyper_5_5_chunk."time"))
-         Sort Method: quicksort 
-         ->  Append (actual rows=4 loops=1)
-               ->  Partial GroupAggregate (actual rows=1 loops=1)
-                     Group Key: time_bucket(10, _hyper_5_5_chunk."time")
-                     ->  Index Scan Backward using _hyper_5_5_chunk_boundary_test_time_idx on _hyper_5_5_chunk (actual rows=1 loops=1)
-                           Index Cond: ("time" >= '-2147483648'::integer)
-               ->  Partial GroupAggregate (actual rows=1 loops=1)
-                     Group Key: time_bucket(10, _hyper_5_6_chunk."time")
-                     ->  Index Scan Backward using _hyper_5_6_chunk_boundary_test_time_idx on _hyper_5_6_chunk (actual rows=1 loops=1)
-                           Index Cond: ("time" >= '-2147483648'::integer)
-               ->  Partial GroupAggregate (actual rows=1 loops=1)
-                     Group Key: time_bucket(10, _hyper_5_7_chunk."time")
-                     ->  Index Scan Backward using _hyper_5_7_chunk_boundary_test_time_idx on _hyper_5_7_chunk (actual rows=1 loops=1)
-                           Index Cond: ("time" >= '-2147483648'::integer)
-               ->  Partial GroupAggregate (actual rows=1 loops=1)
-                     Group Key: time_bucket(10, _hyper_5_8_chunk."time")
-                     ->  Index Scan Backward using _hyper_5_8_chunk_boundary_test_time_idx on _hyper_5_8_chunk (actual rows=1 loops=1)
-                           Index Cond: ("time" >= '-2147483648'::integer)
-(22 rows)
+         ->  Partial GroupAggregate (actual rows=1 loops=1)
+               Group Key: time_bucket(10, _hyper_5_5_chunk."time")
+               ->  Index Scan Backward using _hyper_5_5_chunk_boundary_test_time_idx on _hyper_5_5_chunk (actual rows=1 loops=1)
+                     Index Cond: ("time" >= '-2147483648'::integer)
+         ->  Partial GroupAggregate (actual rows=1 loops=1)
+               Group Key: time_bucket(10, _hyper_5_6_chunk."time")
+               ->  Index Scan Backward using _hyper_5_6_chunk_boundary_test_time_idx on _hyper_5_6_chunk (actual rows=1 loops=1)
+                     Index Cond: ("time" >= '-2147483648'::integer)
+         ->  Partial GroupAggregate (actual rows=1 loops=1)
+               Group Key: time_bucket(10, _hyper_5_7_chunk."time")
+               ->  Index Scan Backward using _hyper_5_7_chunk_boundary_test_time_idx on _hyper_5_7_chunk (actual rows=1 loops=1)
+                     Index Cond: ("time" >= '-2147483648'::integer)
+         ->  Partial GroupAggregate (actual rows=1 loops=1)
+               Group Key: time_bucket(10, _hyper_5_8_chunk."time")
+               ->  Index Scan Backward using _hyper_5_8_chunk_boundary_test_time_idx on _hyper_5_8_chunk (actual rows=1 loops=1)
+                     Index Cond: ("time" >= '-2147483648'::integer)
+(20 rows)
 
 -- result should have 4 rows
 SELECT * FROM boundary_view ORDER BY time_bucket;
@@ -403,26 +401,24 @@ SELECT _timescaledb_functions.cagg_watermark(:boundary_view_id);
 
 -- both sides of the UNION should return 2 rows
 :PREFIX SELECT * FROM boundary_view;
-                                                                 QUERY PLAN                                                                  
----------------------------------------------------------------------------------------------------------------------------------------------
+                                                              QUERY PLAN                                                               
+---------------------------------------------------------------------------------------------------------------------------------------
  Append (actual rows=4 loops=1)
    ->  Index Scan using _hyper_6_9_chunk__materialized_hypertable_6_time_bucket_idx on _hyper_6_9_chunk (actual rows=2 loops=1)
          Index Cond: (time_bucket < 30)
    ->  Finalize GroupAggregate (actual rows=2 loops=1)
          Group Key: (time_bucket(10, _hyper_5_7_chunk."time"))
-         ->  Sort (actual rows=2 loops=1)
+         ->  Merge Append (actual rows=2 loops=1)
                Sort Key: (time_bucket(10, _hyper_5_7_chunk."time"))
-               Sort Method: quicksort 
-               ->  Append (actual rows=2 loops=1)
-                     ->  Partial GroupAggregate (actual rows=1 loops=1)
-                           Group Key: time_bucket(10, _hyper_5_7_chunk."time")
-                           ->  Index Scan Backward using _hyper_5_7_chunk_boundary_test_time_idx on _hyper_5_7_chunk (actual rows=1 loops=1)
-                                 Index Cond: ("time" >= 30)
-                     ->  Partial GroupAggregate (actual rows=1 loops=1)
-                           Group Key: time_bucket(10, _hyper_5_8_chunk."time")
-                           ->  Index Scan Backward using _hyper_5_8_chunk_boundary_test_time_idx on _hyper_5_8_chunk (actual rows=1 loops=1)
-                                 Index Cond: ("time" >= 30)
-(17 rows)
+               ->  Partial GroupAggregate (actual rows=1 loops=1)
+                     Group Key: time_bucket(10, _hyper_5_7_chunk."time")
+                     ->  Index Scan Backward using _hyper_5_7_chunk_boundary_test_time_idx on _hyper_5_7_chunk (actual rows=1 loops=1)
+                           Index Cond: ("time" >= 30)
+               ->  Partial GroupAggregate (actual rows=1 loops=1)
+                     Group Key: time_bucket(10, _hyper_5_8_chunk."time")
+                     ->  Index Scan Backward using _hyper_5_8_chunk_boundary_test_time_idx on _hyper_5_8_chunk (actual rows=1 loops=1)
+                           Index Cond: ("time" >= 30)
+(15 rows)
 
 -- result should have 4 rows
 SELECT * FROM boundary_view ORDER BY time_bucket;
@@ -592,8 +588,8 @@ ORDER by 1;
 
 -- plan output
 :PREFIX SELECT * FROM mat_m1 ORDER BY 1;
-                                                                  QUERY PLAN                                                                   
------------------------------------------------------------------------------------------------------------------------------------------------
+                                                               QUERY PLAN                                                                
+-----------------------------------------------------------------------------------------------------------------------------------------
  Sort (actual rows=3 loops=1)
    Sort Key: _hyper_9_15_chunk.time_bucket
    Sort Method: quicksort 
@@ -604,27 +600,25 @@ ORDER by 1;
                Group Key: (time_bucket(5, _hyper_7_11_chunk.a))
                Filter: ((sum(_hyper_7_11_chunk.c) > 50) AND ((avg(_hyper_7_11_chunk.b))::integer > 12))
                Rows Removed by Filter: 1
-               ->  Sort (actual rows=3 loops=1)
+               ->  Merge Append (actual rows=3 loops=1)
                      Sort Key: (time_bucket(5, _hyper_7_11_chunk.a))
-                     Sort Method: quicksort 
-                     ->  Append (actual rows=3 loops=1)
-                           ->  Partial GroupAggregate (actual rows=1 loops=1)
-                                 Group Key: time_bucket(5, _hyper_7_11_chunk.a)
-                                 ->  Index Scan Backward using _hyper_7_11_chunk_ht_intdata_a_idx on _hyper_7_11_chunk (actual rows=2 loops=1)
-                                       Index Cond: (a >= 25)
-                                       Filter: ((b < 16) AND (c > 20))
-                           ->  Partial GroupAggregate (actual rows=1 loops=1)
-                                 Group Key: time_bucket(5, _hyper_7_13_chunk.a)
-                                 ->  Index Scan Backward using _hyper_7_13_chunk_ht_intdata_a_idx on _hyper_7_13_chunk (actual rows=3 loops=1)
-                                       Index Cond: (a >= 25)
-                                       Filter: ((b < 16) AND (c > 20))
-                           ->  Partial GroupAggregate (actual rows=1 loops=1)
-                                 Group Key: time_bucket(5, _hyper_7_14_chunk.a)
-                                 ->  Index Scan Backward using _hyper_7_14_chunk_ht_intdata_a_idx on _hyper_7_14_chunk (actual rows=1 loops=1)
-                                       Index Cond: (a >= 25)
-                                       Filter: ((b < 16) AND (c > 20))
-                                       Rows Removed by Filter: 2
-(30 rows)
+                     ->  Partial GroupAggregate (actual rows=1 loops=1)
+                           Group Key: time_bucket(5, _hyper_7_11_chunk.a)
+                           ->  Index Scan Backward using _hyper_7_11_chunk_ht_intdata_a_idx on _hyper_7_11_chunk (actual rows=2 loops=1)
+                                 Index Cond: (a >= 25)
+                                 Filter: ((b < 16) AND (c > 20))
+                     ->  Partial GroupAggregate (actual rows=1 loops=1)
+                           Group Key: time_bucket(5, _hyper_7_13_chunk.a)
+                           ->  Index Scan Backward using _hyper_7_13_chunk_ht_intdata_a_idx on _hyper_7_13_chunk (actual rows=3 loops=1)
+                                 Index Cond: (a >= 25)
+                                 Filter: ((b < 16) AND (c > 20))
+                     ->  Partial GroupAggregate (actual rows=1 loops=1)
+                           Group Key: time_bucket(5, _hyper_7_14_chunk.a)
+                           ->  Index Scan Backward using _hyper_7_14_chunk_ht_intdata_a_idx on _hyper_7_14_chunk (actual rows=1 loops=1)
+                                 Index Cond: (a >= 25)
+                                 Filter: ((b < 16) AND (c > 20))
+                                 Rows Removed by Filter: 2
+(28 rows)
 
 -- Test caggs with different time types
 CREATE TABLE smallint_table (time smallint, value int);