Improve EXPLAIN to print the grouping columns in Agg and Group nodes.

Per request from Kevin Grittner.

4 files changed, 20 insertions, 12 deletions

diff --git a/src/test/regress/expected/aggregates.out b/src/test/regress/expected/aggregates.out
index c05b39cb89d..1a0ca5c5f3c 100644
--- a/src/test/regress/expected/aggregates.out
+++ b/src/test/regress/expected/aggregates.out
@@ -659,12 +659,13 @@ explain (costs off)
                              QUERY PLAN                              
 ---------------------------------------------------------------------
  HashAggregate
+   Group Key: $0
    InitPlan 1 (returns $0)
      ->  Limit
            ->  Index Only Scan Backward using tenk1_unique2 on tenk1
                  Index Cond: (unique2 IS NOT NULL)
    ->  Result
-(6 rows)
+(7 rows)
 
 select distinct max(unique2) from tenk1;
  max  
@@ -806,6 +807,7 @@ explain (costs off)
                                           QUERY PLAN                                          
 ----------------------------------------------------------------------------------------------
  HashAggregate
+   Group Key: $0, $1
    InitPlan 1 (returns $0)
      ->  Limit
            ->  Merge Append
@@ -831,7 +833,7 @@ explain (costs off)
                  ->  Index Only Scan Backward using minmaxtest3i on minmaxtest3 minmaxtest3_1
                        Index Cond: (f1 IS NOT NULL)
    ->  Result
-(26 rows)
+(27 rows)
 
 select distinct min(f1), max(f1) from minmaxtest;
  min | max 
diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 9ba2b9a7b48..31751ebd9ed 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -22,8 +22,9 @@ EXPLAIN (costs off)
      QUERY PLAN      
 ---------------------
  HashAggregate
+   Group Key: type
    ->  Seq Scan on t
-(2 rows)
+(3 rows)
 
 CREATE MATERIALIZED VIEW tm AS SELECT type, sum(amt) AS totamt FROM t GROUP BY type WITH NO DATA;
 SELECT relispopulated FROM pg_class WHERE oid = 'tm'::regclass;
@@ -59,8 +60,9 @@ EXPLAIN (costs off)
  Sort
    Sort Key: t.type
    ->  HashAggregate
+         Group Key: t.type
          ->  Seq Scan on t
-(4 rows)
+(5 rows)
 
 CREATE MATERIALIZED VIEW tvm AS SELECT * FROM tv ORDER BY type;
 SELECT * FROM tvm;
@@ -82,8 +84,9 @@ EXPLAIN (costs off)
 ---------------------------
  Aggregate
    ->  HashAggregate
+         Group Key: t.type
          ->  Seq Scan on t
-(3 rows)
+(4 rows)
 
 CREATE MATERIALIZED VIEW tvvm AS SELECT * FROM tvv;
 CREATE VIEW tvvmv AS SELECT * FROM tvvm;
diff --git a/src/test/regress/expected/union.out b/src/test/regress/expected/union.out
index ae690cf9689..6f9ee5eb471 100644
--- a/src/test/regress/expected/union.out
+++ b/src/test/regress/expected/union.out
@@ -494,12 +494,13 @@ explain (costs off)
                     QUERY PLAN                     
 ---------------------------------------------------
  HashAggregate
+   Group Key: ((t1.a || t1.b))
    ->  Append
          ->  Index Scan using t1_ab_idx on t1
                Index Cond: ((a || b) = 'ab'::text)
          ->  Index Only Scan using t2_pkey on t2
                Index Cond: (ab = 'ab'::text)
-(6 rows)
+(7 rows)
 
 reset enable_seqscan;
 reset enable_indexscan;
@@ -552,17 +553,18 @@ SELECT * FROM
    SELECT 2 AS t, 4 AS x) ss
 WHERE x < 4
 ORDER BY x;
-           QUERY PLAN           
---------------------------------
+                       QUERY PLAN                       
+--------------------------------------------------------
  Sort
    Sort Key: ss.x
    ->  Subquery Scan on ss
          Filter: (ss.x < 4)
          ->  HashAggregate
+               Group Key: (1), (generate_series(1, 10))
                ->  Append
                      ->  Result
                      ->  Result
-(8 rows)
+(9 rows)
 
 SELECT * FROM
   (SELECT 1 AS t, generate_series(1,10) AS x
diff --git a/src/test/regress/expected/window.out b/src/test/regress/expected/window.out
index 1e6365b4f9b..0f21fcb01da 100644
--- a/src/test/regress/expected/window.out
+++ b/src/test/regress/expected/window.out
@@ -619,12 +619,13 @@ explain (costs off)
 select first_value(max(x)) over (), y
   from (select unique1 as x, ten+four as y from tenk1) ss
   group by y;
-          QUERY PLAN           
--------------------------------
+                 QUERY PLAN                  
+---------------------------------------------
  WindowAgg
    ->  HashAggregate
+         Group Key: (tenk1.ten + tenk1.four)
          ->  Seq Scan on tenk1
-(3 rows)
+(4 rows)
 
 -- test non-default frame specifications
 SELECT four, ten,