Further adjust EXPLAIN's choices of table alias names.

This patch causes EXPLAIN to always assign a separate table alias to the
parent RTE of an append relation (inheritance set); before, such RTEs
were ignored if not actually scanned by the plan.  Since the child RTEs
now always have that same alias to start with (cf. commit 55a1954da),
the net effect is that the parent RTE usually gets the alias used or
implied by the query text, and the children all get that alias with "_N"
appended.  (The exception to "usually" is if there are duplicate aliases
in different subtrees of the original query; then some of those original
RTEs will also have "_N" appended.)

This results in more uniform output for partitioned-table plans than
we had before: the partitioned table itself gets the original alias,
and all child tables have aliases with "_N", rather than the previous
behavior where one of the children would get an alias without "_N".

The reason for giving the parent RTE an alias, even if it isn't scanned
by the plan, is that we now use the parent's alias to qualify Vars that
refer to an appendrel output column and appear above the Append or
MergeAppend that computes the appendrel.  But below the append, Vars
refer to some one of the child relations, and are displayed that way.
This seems clearer than the old behavior where a Var that could carry
values from any child relation was displayed as if it referred to only
one of them.

While at it, change ruleutils.c so that the code paths used by EXPLAIN
deal in Plan trees not PlanState trees.  This effectively reverts a
decision made in commit 1cc29fe7c, which seemed like a good idea at
the time to make ruleutils.c consistent with explain.c.  However,
it's problematic because we'd really like to allow executor startup
pruning to remove all the children of an append node when possible,
leaving no child PlanState to resolve Vars against.  (That's not done
here, but will be in the next patch.)  This requires different handling
of subplans and initplans than before, but is otherwise a pretty
straightforward change.

Discussion: https://postgr.es/m/[email protected]

1 files changed, 75 insertions, 75 deletions

diff --git a/src/test/regress/expected/partition_aggregate.out b/src/test/regress/expected/partition_aggregate.out
index b3fec2a21cb..fbc8d3ac6c4 100644
--- a/src/test/regress/expected/partition_aggregate.out
+++ b/src/test/regress/expected/partition_aggregate.out
@@ -343,9 +343,9 @@ SELECT c, sum(a) FROM pagg_tab GROUP BY rollup(c) ORDER BY 1, 2;
          Hash Key: pagg_tab.c
          Group Key: ()
          ->  Append
-               ->  Seq Scan on pagg_tab_p1 pagg_tab
-               ->  Seq Scan on pagg_tab_p2 pagg_tab_1
-               ->  Seq Scan on pagg_tab_p3 pagg_tab_2
+               ->  Seq Scan on pagg_tab_p1 pagg_tab_1
+               ->  Seq Scan on pagg_tab_p2 pagg_tab_2
+               ->  Seq Scan on pagg_tab_p3 pagg_tab_3
 (9 rows)
 
 -- ORDERED SET within the aggregate.
@@ -390,9 +390,9 @@ SELECT a, sum(b order by a) FROM pagg_tab GROUP BY a ORDER BY 1, 2;
          ->  Sort
                Sort Key: pagg_tab.a
                ->  Append
-                     ->  Seq Scan on pagg_tab_p1 pagg_tab
-                     ->  Seq Scan on pagg_tab_p2 pagg_tab_1
-                     ->  Seq Scan on pagg_tab_p3 pagg_tab_2
+                     ->  Seq Scan on pagg_tab_p1 pagg_tab_1
+                     ->  Seq Scan on pagg_tab_p2 pagg_tab_2
+                     ->  Seq Scan on pagg_tab_p3 pagg_tab_3
 (10 rows)
 
 -- JOIN query
@@ -461,14 +461,14 @@ SELECT t1.x, sum(t1.y), count(t1) FROM pagg_tab1 t1, pagg_tab2 t2 WHERE t1.x = t
          ->  Hash Join
                Hash Cond: (t1.x = t2.y)
                ->  Append
-                     ->  Seq Scan on pagg_tab1_p1 t1
-                     ->  Seq Scan on pagg_tab1_p2 t1_1
-                     ->  Seq Scan on pagg_tab1_p3 t1_2
+                     ->  Seq Scan on pagg_tab1_p1 t1_1
+                     ->  Seq Scan on pagg_tab1_p2 t1_2
+                     ->  Seq Scan on pagg_tab1_p3 t1_3
                ->  Hash
                      ->  Append
-                           ->  Seq Scan on pagg_tab2_p1 t2
-                           ->  Seq Scan on pagg_tab2_p2 t2_1
-                           ->  Seq Scan on pagg_tab2_p3 t2_2
+                           ->  Seq Scan on pagg_tab2_p1 t2_1
+                           ->  Seq Scan on pagg_tab2_p2 t2_2
+                           ->  Seq Scan on pagg_tab2_p3 t2_3
 (15 rows)
 
 SELECT t1.x, sum(t1.y), count(t1) FROM pagg_tab1 t1, pagg_tab2 t2 WHERE t1.x = t2.y GROUP BY t1.x ORDER BY 1, 2, 3;
@@ -732,15 +732,15 @@ SELECT a.x, b.y, count(*) FROM (SELECT * FROM pagg_tab1 WHERE x < 20) a LEFT JOI
                Hash Cond: (pagg_tab1.x = pagg_tab2.y)
                Filter: ((pagg_tab1.x > 5) OR (pagg_tab2.y < 20))
                ->  Append
-                     ->  Seq Scan on pagg_tab1_p1 pagg_tab1
+                     ->  Seq Scan on pagg_tab1_p1 pagg_tab1_1
                            Filter: (x < 20)
-                     ->  Seq Scan on pagg_tab1_p2 pagg_tab1_1
+                     ->  Seq Scan on pagg_tab1_p2 pagg_tab1_2
                            Filter: (x < 20)
                ->  Hash
                      ->  Append
-                           ->  Seq Scan on pagg_tab2_p2 pagg_tab2
+                           ->  Seq Scan on pagg_tab2_p2 pagg_tab2_1
                                  Filter: (y > 10)
-                           ->  Seq Scan on pagg_tab2_p3 pagg_tab2_1
+                           ->  Seq Scan on pagg_tab2_p3 pagg_tab2_2
                                  Filter: (y > 10)
 (18 rows)
 
@@ -772,15 +772,15 @@ SELECT a.x, b.y, count(*) FROM (SELECT * FROM pagg_tab1 WHERE x < 20) a FULL JOI
                Hash Cond: (pagg_tab1.x = pagg_tab2.y)
                Filter: ((pagg_tab1.x > 5) OR (pagg_tab2.y < 20))
                ->  Append
-                     ->  Seq Scan on pagg_tab1_p1 pagg_tab1
+                     ->  Seq Scan on pagg_tab1_p1 pagg_tab1_1
                            Filter: (x < 20)
-                     ->  Seq Scan on pagg_tab1_p2 pagg_tab1_1
+                     ->  Seq Scan on pagg_tab1_p2 pagg_tab1_2
                            Filter: (x < 20)
                ->  Hash
                      ->  Append
-                           ->  Seq Scan on pagg_tab2_p2 pagg_tab2
+                           ->  Seq Scan on pagg_tab2_p2 pagg_tab2_1
                                  Filter: (y > 10)
-                           ->  Seq Scan on pagg_tab2_p3 pagg_tab2_1
+                           ->  Seq Scan on pagg_tab2_p3 pagg_tab2_2
                                  Filter: (y > 10)
 (18 rows)
 
@@ -946,26 +946,26 @@ SELECT a, sum(b), array_agg(distinct c), count(*) FROM pagg_tab_ml GROUP BY a HA
                                          QUERY PLAN                                         
 --------------------------------------------------------------------------------------------
  Sort
-   Sort Key: pagg_tab_ml_1.a, (sum(pagg_tab_ml_1.b)), (array_agg(DISTINCT pagg_tab_ml_1.c))
+   Sort Key: pagg_tab_ml_2.a, (sum(pagg_tab_ml_2.b)), (array_agg(DISTINCT pagg_tab_ml_2.c))
    ->  Gather
          Workers Planned: 2
          ->  Parallel Append
                ->  GroupAggregate
-                     Group Key: pagg_tab_ml_1.a
-                     Filter: (avg(pagg_tab_ml_1.b) < '3'::numeric)
+                     Group Key: pagg_tab_ml_2.a
+                     Filter: (avg(pagg_tab_ml_2.b) < '3'::numeric)
                      ->  Sort
-                           Sort Key: pagg_tab_ml_1.a
+                           Sort Key: pagg_tab_ml_2.a
                            ->  Append
-                                 ->  Seq Scan on pagg_tab_ml_p2_s1 pagg_tab_ml_1
-                                 ->  Seq Scan on pagg_tab_ml_p2_s2 pagg_tab_ml_2
+                                 ->  Seq Scan on pagg_tab_ml_p2_s1 pagg_tab_ml_2
+                                 ->  Seq Scan on pagg_tab_ml_p2_s2 pagg_tab_ml_3
                ->  GroupAggregate
-                     Group Key: pagg_tab_ml_3.a
-                     Filter: (avg(pagg_tab_ml_3.b) < '3'::numeric)
+                     Group Key: pagg_tab_ml_5.a
+                     Filter: (avg(pagg_tab_ml_5.b) < '3'::numeric)
                      ->  Sort
-                           Sort Key: pagg_tab_ml_3.a
+                           Sort Key: pagg_tab_ml_5.a
                            ->  Append
-                                 ->  Seq Scan on pagg_tab_ml_p3_s1 pagg_tab_ml_3
-                                 ->  Seq Scan on pagg_tab_ml_p3_s2 pagg_tab_ml_4
+                                 ->  Seq Scan on pagg_tab_ml_p3_s1 pagg_tab_ml_5
+                                 ->  Seq Scan on pagg_tab_ml_p3_s2 pagg_tab_ml_6
                ->  GroupAggregate
                      Group Key: pagg_tab_ml.a
                      Filter: (avg(pagg_tab_ml.b) < '3'::numeric)
@@ -997,21 +997,21 @@ SELECT a, sum(b), array_agg(distinct c), count(*) FROM pagg_tab_ml GROUP BY a HA
    Workers Planned: 2
    ->  Parallel Append
          ->  GroupAggregate
-               Group Key: pagg_tab_ml_1.a
-               Filter: (avg(pagg_tab_ml_1.b) < '3'::numeric)
+               Group Key: pagg_tab_ml_2.a
+               Filter: (avg(pagg_tab_ml_2.b) < '3'::numeric)
                ->  Sort
-                     Sort Key: pagg_tab_ml_1.a
+                     Sort Key: pagg_tab_ml_2.a
                      ->  Append
-                           ->  Seq Scan on pagg_tab_ml_p2_s1 pagg_tab_ml_1
-                           ->  Seq Scan on pagg_tab_ml_p2_s2 pagg_tab_ml_2
+                           ->  Seq Scan on pagg_tab_ml_p2_s1 pagg_tab_ml_2
+                           ->  Seq Scan on pagg_tab_ml_p2_s2 pagg_tab_ml_3
          ->  GroupAggregate
-               Group Key: pagg_tab_ml_3.a
-               Filter: (avg(pagg_tab_ml_3.b) < '3'::numeric)
+               Group Key: pagg_tab_ml_5.a
+               Filter: (avg(pagg_tab_ml_5.b) < '3'::numeric)
                ->  Sort
-                     Sort Key: pagg_tab_ml_3.a
+                     Sort Key: pagg_tab_ml_5.a
                      ->  Append
-                           ->  Seq Scan on pagg_tab_ml_p3_s1 pagg_tab_ml_3
-                           ->  Seq Scan on pagg_tab_ml_p3_s2 pagg_tab_ml_4
+                           ->  Seq Scan on pagg_tab_ml_p3_s1 pagg_tab_ml_5
+                           ->  Seq Scan on pagg_tab_ml_p3_s2 pagg_tab_ml_6
          ->  GroupAggregate
                Group Key: pagg_tab_ml.a
                Filter: (avg(pagg_tab_ml.b) < '3'::numeric)
@@ -1035,29 +1035,29 @@ SELECT a, sum(b), count(*) FROM pagg_tab_ml GROUP BY a HAVING avg(b) < 3 ORDER B
                Filter: (avg(pagg_tab_ml.b) < '3'::numeric)
                ->  Seq Scan on pagg_tab_ml_p1 pagg_tab_ml
          ->  Finalize GroupAggregate
-               Group Key: pagg_tab_ml_1.a
-               Filter: (avg(pagg_tab_ml_1.b) < '3'::numeric)
+               Group Key: pagg_tab_ml_2.a
+               Filter: (avg(pagg_tab_ml_2.b) < '3'::numeric)
                ->  Sort
-                     Sort Key: pagg_tab_ml_1.a
+                     Sort Key: pagg_tab_ml_2.a
                      ->  Append
                            ->  Partial HashAggregate
-                                 Group Key: pagg_tab_ml_1.a
-                                 ->  Seq Scan on pagg_tab_ml_p2_s1 pagg_tab_ml_1
-                           ->  Partial HashAggregate
                                  Group Key: pagg_tab_ml_2.a
-                                 ->  Seq Scan on pagg_tab_ml_p2_s2 pagg_tab_ml_2
+                                 ->  Seq Scan on pagg_tab_ml_p2_s1 pagg_tab_ml_2
+                           ->  Partial HashAggregate
+                                 Group Key: pagg_tab_ml_3.a
+                                 ->  Seq Scan on pagg_tab_ml_p2_s2 pagg_tab_ml_3
          ->  Finalize GroupAggregate
-               Group Key: pagg_tab_ml_3.a
-               Filter: (avg(pagg_tab_ml_3.b) < '3'::numeric)
+               Group Key: pagg_tab_ml_5.a
+               Filter: (avg(pagg_tab_ml_5.b) < '3'::numeric)
                ->  Sort
-                     Sort Key: pagg_tab_ml_3.a
+                     Sort Key: pagg_tab_ml_5.a
                      ->  Append
                            ->  Partial HashAggregate
-                                 Group Key: pagg_tab_ml_3.a
-                                 ->  Seq Scan on pagg_tab_ml_p3_s1 pagg_tab_ml_3
+                                 Group Key: pagg_tab_ml_5.a
+                                 ->  Seq Scan on pagg_tab_ml_p3_s1 pagg_tab_ml_5
                            ->  Partial HashAggregate
-                                 Group Key: pagg_tab_ml_4.a
-                                 ->  Seq Scan on pagg_tab_ml_p3_s2 pagg_tab_ml_4
+                                 Group Key: pagg_tab_ml_6.a
+                                 ->  Seq Scan on pagg_tab_ml_p3_s2 pagg_tab_ml_6
 (31 rows)
 
 SELECT a, sum(b), count(*) FROM pagg_tab_ml GROUP BY a HAVING avg(b) < 3 ORDER BY 1, 2, 3;
@@ -1185,33 +1185,33 @@ SELECT a, sum(b), count(*) FROM pagg_tab_ml GROUP BY a HAVING avg(b) < 3 ORDER B
                                  Group Key: pagg_tab_ml.a
                                  ->  Parallel Seq Scan on pagg_tab_ml_p1 pagg_tab_ml
          ->  Finalize GroupAggregate
-               Group Key: pagg_tab_ml_1.a
-               Filter: (avg(pagg_tab_ml_1.b) < '3'::numeric)
+               Group Key: pagg_tab_ml_2.a
+               Filter: (avg(pagg_tab_ml_2.b) < '3'::numeric)
                ->  Gather Merge
                      Workers Planned: 2
                      ->  Sort
-                           Sort Key: pagg_tab_ml_1.a
+                           Sort Key: pagg_tab_ml_2.a
                            ->  Parallel Append
                                  ->  Partial HashAggregate
-                                       Group Key: pagg_tab_ml_1.a
-                                       ->  Parallel Seq Scan on pagg_tab_ml_p2_s1 pagg_tab_ml_1
-                                 ->  Partial HashAggregate
                                        Group Key: pagg_tab_ml_2.a
-                                       ->  Parallel Seq Scan on pagg_tab_ml_p2_s2 pagg_tab_ml_2
+                                       ->  Parallel Seq Scan on pagg_tab_ml_p2_s1 pagg_tab_ml_2
+                                 ->  Partial HashAggregate
+                                       Group Key: pagg_tab_ml_3.a
+                                       ->  Parallel Seq Scan on pagg_tab_ml_p2_s2 pagg_tab_ml_3
          ->  Finalize GroupAggregate
-               Group Key: pagg_tab_ml_3.a
-               Filter: (avg(pagg_tab_ml_3.b) < '3'::numeric)
+               Group Key: pagg_tab_ml_5.a
+               Filter: (avg(pagg_tab_ml_5.b) < '3'::numeric)
                ->  Gather Merge
                      Workers Planned: 2
                      ->  Sort
-                           Sort Key: pagg_tab_ml_3.a
+                           Sort Key: pagg_tab_ml_5.a
                            ->  Parallel Append
                                  ->  Partial HashAggregate
-                                       Group Key: pagg_tab_ml_3.a
-                                       ->  Parallel Seq Scan on pagg_tab_ml_p3_s1 pagg_tab_ml_3
+                                       Group Key: pagg_tab_ml_5.a
+                                       ->  Parallel Seq Scan on pagg_tab_ml_p3_s1 pagg_tab_ml_5
                                  ->  Partial HashAggregate
-                                       Group Key: pagg_tab_ml_4.a
-                                       ->  Parallel Seq Scan on pagg_tab_ml_p3_s2 pagg_tab_ml_4
+                                       Group Key: pagg_tab_ml_6.a
+                                       ->  Parallel Seq Scan on pagg_tab_ml_p3_s2 pagg_tab_ml_6
 (41 rows)
 
 SELECT a, sum(b), count(*) FROM pagg_tab_ml GROUP BY a HAVING avg(b) < 3 ORDER BY 1, 2, 3;
@@ -1426,9 +1426,9 @@ SELECT x, sum(y), avg(y), count(*) FROM pagg_tab_para GROUP BY x HAVING avg(y) <
                      ->  Partial HashAggregate
                            Group Key: pagg_tab_para.x
                            ->  Parallel Append
-                                 ->  Seq Scan on pagg_tab_para_p1 pagg_tab_para
-                                 ->  Seq Scan on pagg_tab_para_p3 pagg_tab_para_2
-                                 ->  Parallel Seq Scan on pagg_tab_para_p2 pagg_tab_para_1
+                                 ->  Seq Scan on pagg_tab_para_p1 pagg_tab_para_1
+                                 ->  Seq Scan on pagg_tab_para_p3 pagg_tab_para_3
+                                 ->  Parallel Seq Scan on pagg_tab_para_p2 pagg_tab_para_2
 (15 rows)
 
 SELECT x, sum(y), avg(y), count(*) FROM pagg_tab_para GROUP BY x HAVING avg(y) < 7 ORDER BY 1, 2, 3;
@@ -1460,9 +1460,9 @@ SELECT x, sum(y), avg(y), count(*) FROM pagg_tab_para GROUP BY x HAVING avg(y) <
                      ->  Partial HashAggregate
                            Group Key: pagg_tab_para.x
                            ->  Parallel Append
-                                 ->  Seq Scan on pagg_tab_para_p1 pagg_tab_para
-                                 ->  Seq Scan on pagg_tab_para_p2 pagg_tab_para_1
-                                 ->  Seq Scan on pagg_tab_para_p3 pagg_tab_para_2
+                                 ->  Seq Scan on pagg_tab_para_p1 pagg_tab_para_1
+                                 ->  Seq Scan on pagg_tab_para_p2 pagg_tab_para_2
+                                 ->  Seq Scan on pagg_tab_para_p3 pagg_tab_para_3
 (15 rows)
 
 SELECT x, sum(y), avg(y), count(*) FROM pagg_tab_para GROUP BY x HAVING avg(y) < 7 ORDER BY 1, 2, 3;