[Answer Query Using Materialized Views] Support GROUP BY, GROUPING SETS, ROLLUP, CUBE in origin query.

[avamingli]

Support Clauses like: Group By column(s), GROUPING SETS, ROLLUP, CUBE in origin query if they could be computed from materialized views's target list.

create incremental materialized view mv as
  select c1 as mc1, c2 as mc2, c3 as mc3
  from t1 where c1 > 90;

Origin query:

  select c1, c3, count(c2) from t1 where c1 > 90
  group by c1, c3;

Could be rewritten to:

  select mc1, mc3, count(mc2) from mv
  group by mc1, mc3;

example DDL

create table aqumv_t3(c1 int, c2 int, c3 int) distributed by (c1);
insert into aqumv_t3 select i, i+1, i+2 from generate_series(1, 100) i;
insert into aqumv_t3 values (91, NULL, 95);
analyze aqumv_t3;
create incremental materialized view aqumv_mvt3_0 as
  select c1 as mc1, c2 as mc2, c3 as mc3
  from aqumv_t3 where c1 > 90;
analyze aqumv_mvt3_0;

Group BY(columns)

explain(costs off, verbose)
select c1, c3, count(c2) from aqumv_t3 where c1 > 90 group by c1, c3;
                                    QUERY PLAN                                    
----------------------------------------------------------------------------------
 Gather Motion 3:1  (slice1; segments: 3)
   Output: mc1, mc3, (count(mc2))
   ->  HashAggregate
         Output: mc1, mc3, count(mc2)
         Group Key: aqumv_mvt3_0.mc1, aqumv_mvt3_0.mc3
         ->  Seq Scan on public.aqumv_mvt3_0
               Output: mc1, mc2, mc3
 Settings: enable_answer_query_using_materialized_views = 'on', optimizer = 'off'
 Optimizer: Postgres query optimizer
(9 rows)

Grouping Sets

explain(costs off, verbose)
select c1, c3, count(c2) from aqumv_t3 where c1 > 90 group by grouping sets((c1), (c3));
                                    QUERY PLAN                                    
----------------------------------------------------------------------------------
 HashAggregate
   Output: mc1, mc3, count(mc2)
   Hash Key: aqumv_mvt3_0.mc1
   Hash Key: aqumv_mvt3_0.mc3
   ->  Gather Motion 3:1  (slice1; segments: 3)
         Output: mc1, mc3, mc2
         ->  Seq Scan on public.aqumv_mvt3_0
               Output: mc1, mc3, mc2
 Settings: enable_answer_query_using_materialized_views = 'on', optimizer = 'off'
 Optimizer: Postgres query optimizer
(10 rows)

ROLLUP

explain(costs off, verbose)
select c1, c3, count(c2) from aqumv_t3 where c1 > 90 group by rollup(c1, c3);
                                    QUERY PLAN                                    
----------------------------------------------------------------------------------
 GroupAggregate
   Output: mc1, mc3, count(mc2)
   Group Key: aqumv_mvt3_0.mc1, aqumv_mvt3_0.mc3
   Group Key: aqumv_mvt3_0.mc1
   Group Key: ()
   ->  Gather Motion 3:1  (slice1; segments: 3)
         Output: mc1, mc3, mc2
         Merge Key: mc1, mc3
         ->  Sort
               Output: mc1, mc3, mc2
               Sort Key: aqumv_mvt3_0.mc1, aqumv_mvt3_0.mc3
               ->  Seq Scan on public.aqumv_mvt3_0
                     Output: mc1, mc3, mc2
 Settings: enable_answer_query_using_materialized_views = 'on', optimizer = 'off'
 Optimizer: Postgres query optimizer
(15 rows)

CUBE

explain(costs off, verbose)
select c1, c3, count(c2) from aqumv_t3 where c1 > 90 group by cube(c1, c3);
                                    QUERY PLAN                                    
----------------------------------------------------------------------------------
 MixedAggregate
   Output: mc1, mc3, count(mc2)
   Hash Key: aqumv_mvt3_0.mc3
   Group Key: aqumv_mvt3_0.mc1, aqumv_mvt3_0.mc3
   Group Key: aqumv_mvt3_0.mc1
   Group Key: ()
   ->  Gather Motion 3:1  (slice1; segments: 3)
         Output: mc1, mc3, mc2
         Merge Key: mc1, mc3
         ->  Sort
               Output: mc1, mc3, mc2
               Sort Key: aqumv_mvt3_0.mc1, aqumv_mvt3_0.mc3
               ->  Seq Scan on public.aqumv_mvt3_0
                     Output: mc1, mc3, mc2
 Settings: enable_answer_query_using_materialized_views = 'on', optimizer = 'off'
 Optimizer: Postgres query optimizer
(16 rows)

Authored-by: Zhang Mingli avamingli@gmail.com

fix #ISSUE_Number

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[avamingli]

Pushed, thanks.