Improve stability of partition_prune regression test.

This test already knew that, to get stable test output, it had to hide
"loops" counts in EXPLAIN ANALYZE results.  But that's not nearly enough:
if we get a smaller number of workers than we planned for, then the
"Workers Launched" number will change, and so will all the rows and loops
counts up to the Gather node.  This has resulted in repeated failures in
the buildfarm, so adjust the test to filter out all these counts.

(Really, we wouldn't bother with EXPLAIN ANALYZE at all here, except
that currently the only way to verify that executor-time pruning has
happened is to look for '(never executed)' annotations.  Those are
stable and needn't be filtered out.)

Back-patch to v11 where the test was introduced.

Discussion: https://postgr.es/m/11952.1569536725@sss.pgh.pa.us

diff --git a/src/test/regress/expected/partition_prune.out b/src/test/regress/expected/partition_prune.out
index d80aa02bb83b789cb4c4c416972f31f420151925..63a5b04cfc0f92f5dcdfad808088cf57728aa90f 100644 (file)
--- a/src/test/regress/expected/partition_prune.out
+++ b/src/test/regress/expected/partition_prune.out
@@ -1972,9 +1972,14 @@ explain (analyze, costs off, summary off, timing off) select * from list_part wh
 rollback;
 drop table list_part;
 -- Parallel append
--- Suppress the number of loops each parallel node runs for.  This is because
--- more than one worker may run the same parallel node if timing conditions
--- are just right, which destabilizes the test.
+-- Parallel queries won't necessarily get as many workers as the planner
+-- asked for.  This affects not only the "Workers Launched:" field of EXPLAIN
+-- results, but also row counts and loop counts for parallel scans, Gathers,
+-- and everything in between.  This function filters out the values we can't
+-- rely on to be stable.
+-- This removes enough info that you might wonder why bother with EXPLAIN
+-- ANALYZE at all.  The answer is that we need to see '(never executed)'
+-- notations because that's the only way to verify runtime pruning.
 create function explain_parallel_append(text) returns setof text
 language plpgsql as
 $$
@@ -1985,9 +1990,8 @@ begin
         execute format('explain (analyze, costs off, summary off, timing off) %s',
             $1)
     loop
-        if ln like '%Parallel%' then
-            ln := regexp_replace(ln, 'loops=\d*',  'loops=N');
-        end if;
+        ln := regexp_replace(ln, 'Workers Launched: \d+', 'Workers Launched: N');
+        ln := regexp_replace(ln, 'actual rows=\d+ loops=\d+', 'actual rows=N loops=N');
         return next ln;
     end loop;
 end;
@@ -2034,18 +2038,18 @@ execute ab_q4 (1, 8);
 select explain_parallel_append('execute ab_q4 (2, 2)');
                             explain_parallel_append                            
 -------------------------------------------------------------------------------
- Finalize Aggregate (actual rows=1 loops=1)
-   ->  Gather (actual rows=3 loops=1)
+ Finalize Aggregate (actual rows=N loops=N)
+   ->  Gather (actual rows=N loops=N)
          Workers Planned: 2
-         Workers Launched: 2
-         ->  Partial Aggregate (actual rows=1 loops=3)
-               ->  Parallel Append (actual rows=0 loops=N)
+         Workers Launched: N
+         ->  Partial Aggregate (actual rows=N loops=N)
+               ->  Parallel Append (actual rows=N loops=N)
                      Subplans Removed: 6
-                     ->  Parallel Seq Scan on ab_a2_b1 (actual rows=0 loops=N)
+                     ->  Parallel Seq Scan on ab_a2_b1 (actual rows=N loops=N)
                            Filter: ((a >= $1) AND (a <= $2) AND (b < 4))
-                     ->  Parallel Seq Scan on ab_a2_b2 (actual rows=0 loops=N)
+                     ->  Parallel Seq Scan on ab_a2_b2 (actual rows=N loops=N)
                            Filter: ((a >= $1) AND (a <= $2) AND (b < 4))
-                     ->  Parallel Seq Scan on ab_a2_b3 (actual rows=0 loops=N)
+                     ->  Parallel Seq Scan on ab_a2_b3 (actual rows=N loops=N)
                            Filter: ((a >= $1) AND (a <= $2) AND (b < 4))
 (13 rows)
 
@@ -2087,42 +2091,42 @@ execute ab_q5 (1, 2, 3);
 select explain_parallel_append('execute ab_q5 (1, 1, 1)');
                             explain_parallel_append                            
 -------------------------------------------------------------------------------
- Finalize Aggregate (actual rows=1 loops=1)
-   ->  Gather (actual rows=3 loops=1)
+ Finalize Aggregate (actual rows=N loops=N)
+   ->  Gather (actual rows=N loops=N)
          Workers Planned: 2
-         Workers Launched: 2
-         ->  Partial Aggregate (actual rows=1 loops=3)
-               ->  Parallel Append (actual rows=0 loops=N)
+         Workers Launched: N
+         ->  Partial Aggregate (actual rows=N loops=N)
+               ->  Parallel Append (actual rows=N loops=N)
                      Subplans Removed: 6
-                     ->  Parallel Seq Scan on ab_a1_b1 (actual rows=0 loops=N)
+                     ->  Parallel Seq Scan on ab_a1_b1 (actual rows=N loops=N)
                            Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
-                     ->  Parallel Seq Scan on ab_a1_b2 (actual rows=0 loops=N)
+                     ->  Parallel Seq Scan on ab_a1_b2 (actual rows=N loops=N)
                            Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
-                     ->  Parallel Seq Scan on ab_a1_b3 (actual rows=0 loops=N)
+                     ->  Parallel Seq Scan on ab_a1_b3 (actual rows=N loops=N)
                            Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
 (13 rows)
 
 select explain_parallel_append('execute ab_q5 (2, 3, 3)');
                             explain_parallel_append                            
 -------------------------------------------------------------------------------
- Finalize Aggregate (actual rows=1 loops=1)
-   ->  Gather (actual rows=3 loops=1)
+ Finalize Aggregate (actual rows=N loops=N)
+   ->  Gather (actual rows=N loops=N)
          Workers Planned: 2
-         Workers Launched: 2
-         ->  Partial Aggregate (actual rows=1 loops=3)
-               ->  Parallel Append (actual rows=0 loops=N)
+         Workers Launched: N
+         ->  Partial Aggregate (actual rows=N loops=N)
+               ->  Parallel Append (actual rows=N loops=N)
                      Subplans Removed: 3
-                     ->  Parallel Seq Scan on ab_a2_b1 (actual rows=0 loops=N)
+                     ->  Parallel Seq Scan on ab_a2_b1 (actual rows=N loops=N)
                            Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
-                     ->  Parallel Seq Scan on ab_a2_b2 (actual rows=0 loops=N)
+                     ->  Parallel Seq Scan on ab_a2_b2 (actual rows=N loops=N)
                            Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
-                     ->  Parallel Seq Scan on ab_a2_b3 (actual rows=0 loops=N)
+                     ->  Parallel Seq Scan on ab_a2_b3 (actual rows=N loops=N)
                            Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
-                     ->  Parallel Seq Scan on ab_a3_b1 (actual rows=0 loops=N)
+                     ->  Parallel Seq Scan on ab_a3_b1 (actual rows=N loops=N)
                            Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
-                     ->  Parallel Seq Scan on ab_a3_b2 (actual rows=0 loops=N)
+                     ->  Parallel Seq Scan on ab_a3_b2 (actual rows=N loops=N)
                            Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
-                     ->  Parallel Seq Scan on ab_a3_b3 (actual rows=0 loops=N)
+                     ->  Parallel Seq Scan on ab_a3_b3 (actual rows=N loops=N)
                            Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
 (19 rows)
 
@@ -2131,12 +2135,12 @@ select explain_parallel_append('execute ab_q5 (2, 3, 3)');
 select explain_parallel_append('execute ab_q5 (33, 44, 55)');
                             explain_parallel_append                            
 -------------------------------------------------------------------------------
- Finalize Aggregate (actual rows=1 loops=1)
-   ->  Gather (actual rows=3 loops=1)
+ Finalize Aggregate (actual rows=N loops=N)
+   ->  Gather (actual rows=N loops=N)
          Workers Planned: 2
-         Workers Launched: 2
-         ->  Partial Aggregate (actual rows=1 loops=3)
-               ->  Parallel Append (actual rows=0 loops=N)
+         Workers Launched: N
+         ->  Partial Aggregate (actual rows=N loops=N)
+               ->  Parallel Append (actual rows=N loops=N)
                      Subplans Removed: 8
                      ->  Parallel Seq Scan on ab_a1_b1 (never executed)
                            Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
@@ -2146,21 +2150,21 @@ select explain_parallel_append('execute ab_q5 (33, 44, 55)');
 select explain_parallel_append('select count(*) from ab where (a = (select 1) or a = (select 3)) and b = 2');
                          explain_parallel_append                         
 -------------------------------------------------------------------------
- Aggregate (actual rows=1 loops=1)
+ Aggregate (actual rows=N loops=N)
    InitPlan 1 (returns $0)
-     ->  Result (actual rows=1 loops=1)
+     ->  Result (actual rows=N loops=N)
    InitPlan 2 (returns $1)
-     ->  Result (actual rows=1 loops=1)
-   ->  Gather (actual rows=0 loops=1)
+     ->  Result (actual rows=N loops=N)
+   ->  Gather (actual rows=N loops=N)
          Workers Planned: 2
          Params Evaluated: $0, $1
-         Workers Launched: 2
-         ->  Parallel Append (actual rows=0 loops=N)
-               ->  Parallel Seq Scan on ab_a1_b2 (actual rows=0 loops=N)
+         Workers Launched: N
+         ->  Parallel Append (actual rows=N loops=N)
+               ->  Parallel Seq Scan on ab_a1_b2 (actual rows=N loops=N)
                      Filter: ((b = 2) AND ((a = $0) OR (a = $1)))
                ->  Parallel Seq Scan on ab_a2_b2 (never executed)
                      Filter: ((b = 2) AND ((a = $0) OR (a = $1)))
-               ->  Parallel Seq Scan on ab_a3_b2 (actual rows=0 loops=N)
+               ->  Parallel Seq Scan on ab_a3_b2 (actual rows=N loops=N)
                      Filter: ((b = 2) AND ((a = $0) OR (a = $1)))
 (16 rows)
 
@@ -2185,20 +2189,20 @@ set enable_mergejoin = 0;
 select explain_parallel_append('select avg(ab.a) from ab inner join lprt_a a on ab.a = a.a where a.a in(0, 0, 1)');
                                       explain_parallel_append                                      
 ---------------------------------------------------------------------------------------------------
- Finalize Aggregate (actual rows=1 loops=1)
-   ->  Gather (actual rows=2 loops=1)
+ Finalize Aggregate (actual rows=N loops=N)
+   ->  Gather (actual rows=N loops=N)
          Workers Planned: 1
-         Workers Launched: 1
-         ->  Partial Aggregate (actual rows=1 loops=2)
-               ->  Nested Loop (actual rows=0 loops=2)
-                     ->  Parallel Seq Scan on lprt_a a (actual rows=51 loops=N)
+         Workers Launched: N
+         ->  Partial Aggregate (actual rows=N loops=N)
+               ->  Nested Loop (actual rows=N loops=N)
+                     ->  Parallel Seq Scan on lprt_a a (actual rows=N loops=N)
                            Filter: (a = ANY ('{0,0,1}'::integer[]))
-                     ->  Append (actual rows=0 loops=102)
-                           ->  Index Scan using ab_a1_b1_a_idx on ab_a1_b1 (actual rows=0 loops=2)
+                     ->  Append (actual rows=N loops=N)
+                           ->  Index Scan using ab_a1_b1_a_idx on ab_a1_b1 (actual rows=N loops=N)
                                  Index Cond: (a = a.a)
-                           ->  Index Scan using ab_a1_b2_a_idx on ab_a1_b2 (actual rows=0 loops=2)
+                           ->  Index Scan using ab_a1_b2_a_idx on ab_a1_b2 (actual rows=N loops=N)
                                  Index Cond: (a = a.a)
-                           ->  Index Scan using ab_a1_b3_a_idx on ab_a1_b3 (actual rows=0 loops=2)
+                           ->  Index Scan using ab_a1_b3_a_idx on ab_a1_b3 (actual rows=N loops=N)
                                  Index Cond: (a = a.a)
                            ->  Index Scan using ab_a2_b1_a_idx on ab_a2_b1 (never executed)
                                  Index Cond: (a = a.a)
@@ -2219,20 +2223,20 @@ select explain_parallel_append('select avg(ab.a) from ab inner join lprt_a a on
 select explain_parallel_append('select avg(ab.a) from ab inner join lprt_a a on ab.a = a.a + 0 where a.a in(0, 0, 1)');
                                       explain_parallel_append                                      
 ---------------------------------------------------------------------------------------------------
- Finalize Aggregate (actual rows=1 loops=1)
-   ->  Gather (actual rows=2 loops=1)
+ Finalize Aggregate (actual rows=N loops=N)
+   ->  Gather (actual rows=N loops=N)
          Workers Planned: 1
-         Workers Launched: 1
-         ->  Partial Aggregate (actual rows=1 loops=2)
-               ->  Nested Loop (actual rows=0 loops=2)
-                     ->  Parallel Seq Scan on lprt_a a (actual rows=51 loops=N)
+         Workers Launched: N
+         ->  Partial Aggregate (actual rows=N loops=N)
+               ->  Nested Loop (actual rows=N loops=N)
+                     ->  Parallel Seq Scan on lprt_a a (actual rows=N loops=N)
                            Filter: (a = ANY ('{0,0,1}'::integer[]))
-                     ->  Append (actual rows=0 loops=102)
-                           ->  Index Scan using ab_a1_b1_a_idx on ab_a1_b1 (actual rows=0 loops=2)
+                     ->  Append (actual rows=N loops=N)
+                           ->  Index Scan using ab_a1_b1_a_idx on ab_a1_b1 (actual rows=N loops=N)
                                  Index Cond: (a = (a.a + 0))
-                           ->  Index Scan using ab_a1_b2_a_idx on ab_a1_b2 (actual rows=0 loops=2)
+                           ->  Index Scan using ab_a1_b2_a_idx on ab_a1_b2 (actual rows=N loops=N)
                                  Index Cond: (a = (a.a + 0))
-                           ->  Index Scan using ab_a1_b3_a_idx on ab_a1_b3 (actual rows=0 loops=2)
+                           ->  Index Scan using ab_a1_b3_a_idx on ab_a1_b3 (actual rows=N loops=N)
                                  Index Cond: (a = (a.a + 0))
                            ->  Index Scan using ab_a2_b1_a_idx on ab_a2_b1 (never executed)
                                  Index Cond: (a = (a.a + 0))
@@ -2252,20 +2256,20 @@ insert into lprt_a values(3),(3);
 select explain_parallel_append('select avg(ab.a) from ab inner join lprt_a a on ab.a = a.a where a.a in(1, 0, 3)');
                                       explain_parallel_append                                      
 ---------------------------------------------------------------------------------------------------
- Finalize Aggregate (actual rows=1 loops=1)
-   ->  Gather (actual rows=2 loops=1)
+ Finalize Aggregate (actual rows=N loops=N)
+   ->  Gather (actual rows=N loops=N)
          Workers Planned: 1
-         Workers Launched: 1
-         ->  Partial Aggregate (actual rows=1 loops=2)
-               ->  Nested Loop (actual rows=0 loops=2)
-                     ->  Parallel Seq Scan on lprt_a a (actual rows=52 loops=N)
+         Workers Launched: N
+         ->  Partial Aggregate (actual rows=N loops=N)
+               ->  Nested Loop (actual rows=N loops=N)
+                     ->  Parallel Seq Scan on lprt_a a (actual rows=N loops=N)
                            Filter: (a = ANY ('{1,0,3}'::integer[]))
-                     ->  Append (actual rows=0 loops=104)
-                           ->  Index Scan using ab_a1_b1_a_idx on ab_a1_b1 (actual rows=0 loops=2)
+                     ->  Append (actual rows=N loops=N)
+                           ->  Index Scan using ab_a1_b1_a_idx on ab_a1_b1 (actual rows=N loops=N)
                                  Index Cond: (a = a.a)
-                           ->  Index Scan using ab_a1_b2_a_idx on ab_a1_b2 (actual rows=0 loops=2)
+                           ->  Index Scan using ab_a1_b2_a_idx on ab_a1_b2 (actual rows=N loops=N)
                                  Index Cond: (a = a.a)
-                           ->  Index Scan using ab_a1_b3_a_idx on ab_a1_b3 (actual rows=0 loops=2)
+                           ->  Index Scan using ab_a1_b3_a_idx on ab_a1_b3 (actual rows=N loops=N)
                                  Index Cond: (a = a.a)
                            ->  Index Scan using ab_a2_b1_a_idx on ab_a2_b1 (never executed)
                                  Index Cond: (a = a.a)
@@ -2273,32 +2277,32 @@ select explain_parallel_append('select avg(ab.a) from ab inner join lprt_a a on
                                  Index Cond: (a = a.a)
                            ->  Index Scan using ab_a2_b3_a_idx on ab_a2_b3 (never executed)
                                  Index Cond: (a = a.a)
-                           ->  Index Scan using ab_a3_b1_a_idx on ab_a3_b1 (actual rows=0 loops=2)
+                           ->  Index Scan using ab_a3_b1_a_idx on ab_a3_b1 (actual rows=N loops=N)
                                  Index Cond: (a = a.a)
-                           ->  Index Scan using ab_a3_b2_a_idx on ab_a3_b2 (actual rows=0 loops=2)
+                           ->  Index Scan using ab_a3_b2_a_idx on ab_a3_b2 (actual rows=N loops=N)
                                  Index Cond: (a = a.a)
-                           ->  Index Scan using ab_a3_b3_a_idx on ab_a3_b3 (actual rows=0 loops=2)
+                           ->  Index Scan using ab_a3_b3_a_idx on ab_a3_b3 (actual rows=N loops=N)
                                  Index Cond: (a = a.a)
 (27 rows)
 
 select explain_parallel_append('select avg(ab.a) from ab inner join lprt_a a on ab.a = a.a where a.a in(1, 0, 0)');
                                       explain_parallel_append                                      
 ---------------------------------------------------------------------------------------------------
- Finalize Aggregate (actual rows=1 loops=1)
-   ->  Gather (actual rows=2 loops=1)
+ Finalize Aggregate (actual rows=N loops=N)
+   ->  Gather (actual rows=N loops=N)
          Workers Planned: 1
-         Workers Launched: 1
-         ->  Partial Aggregate (actual rows=1 loops=2)
-               ->  Nested Loop (actual rows=0 loops=2)
-                     ->  Parallel Seq Scan on lprt_a a (actual rows=51 loops=N)
+         Workers Launched: N
+         ->  Partial Aggregate (actual rows=N loops=N)
+               ->  Nested Loop (actual rows=N loops=N)
+                     ->  Parallel Seq Scan on lprt_a a (actual rows=N loops=N)
                            Filter: (a = ANY ('{1,0,0}'::integer[]))
                            Rows Removed by Filter: 1
-                     ->  Append (actual rows=0 loops=102)
-                           ->  Index Scan using ab_a1_b1_a_idx on ab_a1_b1 (actual rows=0 loops=2)
+                     ->  Append (actual rows=N loops=N)
+                           ->  Index Scan using ab_a1_b1_a_idx on ab_a1_b1 (actual rows=N loops=N)
                                  Index Cond: (a = a.a)
-                           ->  Index Scan using ab_a1_b2_a_idx on ab_a1_b2 (actual rows=0 loops=2)
+                           ->  Index Scan using ab_a1_b2_a_idx on ab_a1_b2 (actual rows=N loops=N)
                                  Index Cond: (a = a.a)
-                           ->  Index Scan using ab_a1_b3_a_idx on ab_a1_b3 (actual rows=0 loops=2)
+                           ->  Index Scan using ab_a1_b3_a_idx on ab_a1_b3 (actual rows=N loops=N)
                                  Index Cond: (a = a.a)
                            ->  Index Scan using ab_a2_b1_a_idx on ab_a2_b1 (never executed)
                                  Index Cond: (a = a.a)
@@ -2318,16 +2322,16 @@ delete from lprt_a where a = 1;
 select explain_parallel_append('select avg(ab.a) from ab inner join lprt_a a on ab.a = a.a where a.a in(1, 0, 0)');
                                   explain_parallel_append                                   
 --------------------------------------------------------------------------------------------
- Finalize Aggregate (actual rows=1 loops=1)
-   ->  Gather (actual rows=2 loops=1)
+ Finalize Aggregate (actual rows=N loops=N)
+   ->  Gather (actual rows=N loops=N)
          Workers Planned: 1
-         Workers Launched: 1
-         ->  Partial Aggregate (actual rows=1 loops=2)
-               ->  Nested Loop (actual rows=0 loops=2)
-                     ->  Parallel Seq Scan on lprt_a a (actual rows=50 loops=N)
+         Workers Launched: N
+         ->  Partial Aggregate (actual rows=N loops=N)
+               ->  Nested Loop (actual rows=N loops=N)
+                     ->  Parallel Seq Scan on lprt_a a (actual rows=N loops=N)
                            Filter: (a = ANY ('{1,0,0}'::integer[]))
                            Rows Removed by Filter: 1
-                     ->  Append (actual rows=0 loops=100)
+                     ->  Append (actual rows=N loops=N)
                            ->  Index Scan using ab_a1_b1_a_idx on ab_a1_b1 (never executed)
                                  Index Cond: (a = a.a)
                            ->  Index Scan using ab_a1_b2_a_idx on ab_a1_b2 (never executed)

diff --git a/src/test/regress/sql/partition_prune.sql b/src/test/regress/sql/partition_prune.sql
index ac12b891ae205066222e7052f4bbc8ce6db4bd74..58de9cc621df6e5005ddaa9910e7aa4e06d3bd89 100644 (file)
--- a/src/test/regress/sql/partition_prune.sql
+++ b/src/test/regress/sql/partition_prune.sql
@@ -447,9 +447,14 @@ drop table list_part;
 
 -- Parallel append
 
--- Suppress the number of loops each parallel node runs for.  This is because
--- more than one worker may run the same parallel node if timing conditions
--- are just right, which destabilizes the test.
+-- Parallel queries won't necessarily get as many workers as the planner
+-- asked for.  This affects not only the "Workers Launched:" field of EXPLAIN
+-- results, but also row counts and loop counts for parallel scans, Gathers,
+-- and everything in between.  This function filters out the values we can't
+-- rely on to be stable.
+-- This removes enough info that you might wonder why bother with EXPLAIN
+-- ANALYZE at all.  The answer is that we need to see '(never executed)'
+-- notations because that's the only way to verify runtime pruning.
 create function explain_parallel_append(text) returns setof text
 language plpgsql as
 $$
@@ -460,9 +465,8 @@ begin
         execute format('explain (analyze, costs off, summary off, timing off) %s',
             $1)
     loop
-        if ln like '%Parallel%' then
-            ln := regexp_replace(ln, 'loops=\d*',  'loops=N');
-        end if;
+        ln := regexp_replace(ln, 'Workers Launched: \d+', 'Workers Launched: N');
+        ln := regexp_replace(ln, 'actual rows=\d+ loops=\d+', 'actual rows=N loops=N');
         return next ln;
     end loop;
 end;