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Restore partition_prune's usage of parallel workers

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This reverts commit 4d0f6d3f207d ("Attempt to stabilize partition_prune
test output (2)"), and attempts to stabilize the test by using string
replacement to hide any loop count difference in parallel nodes.

Discussion: https://postgr.es/m/4475.1523628300@sss.pgh.pa.us
This commit is contained in:
Alvaro Herrera 2018-04-16 18:12:22 -03:00
parent b15e8f71db
commit 47c91b5599
2 changed files with 109 additions and 74 deletions
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144
src/test/regress/expected/partition_prune.out
View File

@ -1748,16 +1748,34 @@ explain (analyze, costs off, summary off, timing off) execute ab_q3 (2, 2);
(10 rows) (10 rows)
-- Parallel append -- 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.
create function explain_parallel_append(text, int[]) returns setof text
language plpgsql as
$$
declare
ln text;
args text := string_agg(u::text, ', ') from unnest($2) u;
begin
for ln in
execute format('explain (analyze, costs off, summary off, timing off) execute %s(%s)',
$1, args)
loop
if ln like '%Parallel%' then
ln := regexp_replace(ln, 'loops=\d*', 'loops=N');
end if;
return next ln;
end loop;
end;
$$;
prepare ab_q4 (int, int) as prepare ab_q4 (int, int) as
select avg(a) from ab where a between $1 and $2 and b < 4; select avg(a) from ab where a between $1 and $2 and b < 4;
-- Encourage use of parallel plans -- Encourage use of parallel plans
set parallel_setup_cost = 0; set parallel_setup_cost = 0;
set parallel_tuple_cost = 0; set parallel_tuple_cost = 0;
set min_parallel_table_scan_size = 0; set min_parallel_table_scan_size = 0;
-- set this so we get a parallel plan
set max_parallel_workers_per_gather = 2; set max_parallel_workers_per_gather = 2;
-- and zero this so that workers don't destabilize the explain output
set max_parallel_workers = 0;
-- Execute query 5 times to allow choose_custom_plan -- Execute query 5 times to allow choose_custom_plan
-- to start considering a generic plan. -- to start considering a generic plan.
execute ab_q4 (1, 8); execute ab_q4 (1, 8);
@ -1790,21 +1808,21 @@ execute ab_q4 (1, 8);
(1 row) (1 row)
explain (analyze, costs off, summary off, timing off) execute ab_q4 (2, 2); select explain_parallel_append('ab_q4', '{2, 2}');
QUERY PLAN explain_parallel_append
------------------------------------------------------------------------------- -------------------------------------------------------------------------------
Finalize Aggregate (actual rows=1 loops=1) Finalize Aggregate (actual rows=1 loops=1)
-> Gather (actual rows=1 loops=1) -> Gather (actual rows=3 loops=1)
Workers Planned: 2 Workers Planned: 2
Workers Launched: 0 Workers Launched: 2
-> Partial Aggregate (actual rows=1 loops=1) -> Partial Aggregate (actual rows=1 loops=3)
-> Parallel Append (actual rows=0 loops=1) -> Parallel Append (actual rows=0 loops=N)
Subplans Removed: 6 Subplans Removed: 6
-> Parallel Seq Scan on ab_a2_b1 (actual rows=0 loops=1) -> Parallel Seq Scan on ab_a2_b1 (actual rows=0 loops=N)
Filter: ((a >= $1) AND (a <= $2) AND (b < 4)) Filter: ((a >= $1) AND (a <= $2) AND (b < 4))
-> Parallel Seq Scan on ab_a2_b2 (actual rows=0 loops=1) -> Parallel Seq Scan on ab_a2_b2 (actual rows=0 loops=N)
Filter: ((a >= $1) AND (a <= $2) AND (b < 4)) Filter: ((a >= $1) AND (a <= $2) AND (b < 4))
-> Parallel Seq Scan on ab_a2_b3 (actual rows=0 loops=1) -> Parallel Seq Scan on ab_a2_b3 (actual rows=0 loops=N)
Filter: ((a >= $1) AND (a <= $2) AND (b < 4)) Filter: ((a >= $1) AND (a <= $2) AND (b < 4))
(13 rows) (13 rows)
@ -1843,59 +1861,59 @@ execute ab_q5 (1, 2, 3);
(1 row) (1 row)
explain (analyze, costs off, summary off, timing off) execute ab_q5 (1, 1, 1); select explain_parallel_append('ab_q5', '{1, 1, 1}');
QUERY PLAN explain_parallel_append
------------------------------------------------------------------------------- -------------------------------------------------------------------------------
Finalize Aggregate (actual rows=1 loops=1) Finalize Aggregate (actual rows=1 loops=1)
-> Gather (actual rows=1 loops=1) -> Gather (actual rows=3 loops=1)
Workers Planned: 2 Workers Planned: 2
Workers Launched: 0 Workers Launched: 2
-> Partial Aggregate (actual rows=1 loops=1) -> Partial Aggregate (actual rows=1 loops=3)
-> Parallel Append (actual rows=0 loops=1) -> Parallel Append (actual rows=0 loops=N)
Subplans Removed: 6 Subplans Removed: 6
-> Parallel Seq Scan on ab_a1_b1 (actual rows=0 loops=1) -> Parallel Seq Scan on ab_a1_b1 (actual rows=0 loops=N)
Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3]))) Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
-> Parallel Seq Scan on ab_a1_b2 (actual rows=0 loops=1) -> Parallel Seq Scan on ab_a1_b2 (actual rows=0 loops=N)
Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3]))) Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
-> Parallel Seq Scan on ab_a1_b3 (actual rows=0 loops=1) -> Parallel Seq Scan on ab_a1_b3 (actual rows=0 loops=N)
Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3]))) Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
(13 rows) (13 rows)
explain (analyze, costs off, summary off, timing off) execute ab_q5 (2, 3, 3); select explain_parallel_append('ab_q5', '{2, 3, 3}');
QUERY PLAN explain_parallel_append
------------------------------------------------------------------------------- -------------------------------------------------------------------------------
Finalize Aggregate (actual rows=1 loops=1) Finalize Aggregate (actual rows=1 loops=1)
-> Gather (actual rows=1 loops=1) -> Gather (actual rows=3 loops=1)
Workers Planned: 2 Workers Planned: 2
Workers Launched: 0 Workers Launched: 2
-> Partial Aggregate (actual rows=1 loops=1) -> Partial Aggregate (actual rows=1 loops=3)
-> Parallel Append (actual rows=0 loops=1) -> Parallel Append (actual rows=0 loops=N)
Subplans Removed: 3 Subplans Removed: 3
-> Parallel Seq Scan on ab_a2_b1 (actual rows=0 loops=1) -> Parallel Seq Scan on ab_a2_b1 (actual rows=0 loops=N)
Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3]))) Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
-> Parallel Seq Scan on ab_a2_b2 (actual rows=0 loops=1) -> Parallel Seq Scan on ab_a2_b2 (actual rows=0 loops=N)
Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3]))) Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
-> Parallel Seq Scan on ab_a2_b3 (actual rows=0 loops=1) -> Parallel Seq Scan on ab_a2_b3 (actual rows=0 loops=N)
Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3]))) Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
-> Parallel Seq Scan on ab_a3_b1 (actual rows=0 loops=1) -> Parallel Seq Scan on ab_a3_b1 (actual rows=0 loops=N)
Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3]))) Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
-> Parallel Seq Scan on ab_a3_b2 (actual rows=0 loops=1) -> Parallel Seq Scan on ab_a3_b2 (actual rows=0 loops=N)
Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3]))) Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
-> Parallel Seq Scan on ab_a3_b3 (actual rows=0 loops=1) -> Parallel Seq Scan on ab_a3_b3 (actual rows=0 loops=N)
Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3]))) Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
(19 rows) (19 rows)
-- Try some params whose values do not belong to any partition. -- Try some params whose values do not belong to any partition.
-- We'll still get a single subplan in this case, but it should not be scanned. -- We'll still get a single subplan in this case, but it should not be scanned.
explain (analyze, costs off, summary off, timing off) execute ab_q5 (33, 44, 55); select explain_parallel_append('ab_q5', '{33, 44, 55}');
QUERY PLAN explain_parallel_append
------------------------------------------------------------------------------- -------------------------------------------------------------------------------
Finalize Aggregate (actual rows=1 loops=1) Finalize Aggregate (actual rows=1 loops=1)
-> Gather (actual rows=1 loops=1) -> Gather (actual rows=3 loops=1)
Workers Planned: 2 Workers Planned: 2
Workers Launched: 0 Workers Launched: 2
-> Partial Aggregate (actual rows=1 loops=1) -> Partial Aggregate (actual rows=1 loops=3)
-> Parallel Append (actual rows=0 loops=1) -> Parallel Append (actual rows=0 loops=N)
Subplans Removed: 8 Subplans Removed: 8
-> Parallel Seq Scan on ab_a1_b1 (never executed) -> Parallel Seq Scan on ab_a1_b1 (never executed)
Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3]))) Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
@ -1951,16 +1969,16 @@ execute ab_q6 (1, 2, 3);
(1 row) (1 row)
explain (analyze, costs off, summary off, timing off) execute ab_q6 (0, 0, 1); select explain_parallel_append('ab_q6', '{0, 0, 1}');
QUERY PLAN explain_parallel_append
--------------------------------------------------------------------------------------------------- ---------------------------------------------------------------------------------------------------
Finalize Aggregate (actual rows=1 loops=1) Finalize Aggregate (actual rows=1 loops=1)
-> Gather (actual rows=1 loops=1) -> Gather (actual rows=2 loops=1)
Workers Planned: 1 Workers Planned: 1
Workers Launched: 0 Workers Launched: 1
-> Partial Aggregate (actual rows=1 loops=1) -> Partial Aggregate (actual rows=1 loops=2)
-> Nested Loop (actual rows=0 loops=1) -> Nested Loop (actual rows=0 loops=2)
-> Parallel Seq Scan on lprt_a a (actual rows=102 loops=1) -> Parallel Seq Scan on lprt_a a (actual rows=51 loops=N)
Filter: (a = ANY ('{0,0,1}'::integer[])) Filter: (a = ANY ('{0,0,1}'::integer[]))
-> Append (actual rows=0 loops=102) -> Append (actual rows=0 loops=102)
-> Index Scan using ab_a1_b1_a_idx on ab_a1_b1 (actual rows=0 loops=2) -> Index Scan using ab_a1_b1_a_idx on ab_a1_b1 (actual rows=0 loops=2)
@ -1988,12 +2006,12 @@ explain (analyze, costs off, summary off, timing off) execute ab_q6 (1, 0, 3);
QUERY PLAN QUERY PLAN
--------------------------------------------------------------------------------------------------- ---------------------------------------------------------------------------------------------------
Finalize Aggregate (actual rows=1 loops=1) Finalize Aggregate (actual rows=1 loops=1)
-> Gather (actual rows=1 loops=1) -> Gather (actual rows=2 loops=1)
Workers Planned: 1 Workers Planned: 1
Workers Launched: 0 Workers Launched: 1
-> Partial Aggregate (actual rows=1 loops=1) -> Partial Aggregate (actual rows=1 loops=2)
-> Nested Loop (actual rows=0 loops=1) -> Nested Loop (actual rows=0 loops=2)
-> Parallel Seq Scan on lprt_a a (actual rows=104 loops=1) -> Parallel Seq Scan on lprt_a a (actual rows=52 loops=2)
Filter: (a = ANY ('{1,0,3}'::integer[])) Filter: (a = ANY ('{1,0,3}'::integer[]))
-> Append (actual rows=0 loops=104) -> Append (actual rows=0 loops=104)
-> Index Scan using ab_a1_b1_a_idx on ab_a1_b1 (actual rows=0 loops=2) -> Index Scan using ab_a1_b1_a_idx on ab_a1_b1 (actual rows=0 loops=2)
@ -2020,14 +2038,14 @@ explain (analyze, costs off, summary off, timing off) execute ab_q6 (1, 0, 0);
QUERY PLAN QUERY PLAN
--------------------------------------------------------------------------------------------------- ---------------------------------------------------------------------------------------------------
Finalize Aggregate (actual rows=1 loops=1) Finalize Aggregate (actual rows=1 loops=1)
-> Gather (actual rows=1 loops=1) -> Gather (actual rows=2 loops=1)
Workers Planned: 1 Workers Planned: 1
Workers Launched: 0 Workers Launched: 1
-> Partial Aggregate (actual rows=1 loops=1) -> Partial Aggregate (actual rows=1 loops=2)
-> Nested Loop (actual rows=0 loops=1) -> Nested Loop (actual rows=0 loops=2)
-> Parallel Seq Scan on lprt_a a (actual rows=102 loops=1) -> Parallel Seq Scan on lprt_a a (actual rows=51 loops=2)
Filter: (a = ANY ('{1,0,0}'::integer[])) Filter: (a = ANY ('{1,0,0}'::integer[]))
Rows Removed by Filter: 2 Rows Removed by Filter: 1
-> Append (actual rows=0 loops=102) -> Append (actual rows=0 loops=102)
-> Index Scan using ab_a1_b1_a_idx on ab_a1_b1 (actual rows=0 loops=2) -> Index Scan using ab_a1_b1_a_idx on ab_a1_b1 (actual rows=0 loops=2)
Index Cond: (a = a.a) Index Cond: (a = a.a)
@ -2054,14 +2072,14 @@ explain (analyze, costs off, summary off, timing off) execute ab_q6 (1, 0, 0);
QUERY PLAN QUERY PLAN
-------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------
Finalize Aggregate (actual rows=1 loops=1) Finalize Aggregate (actual rows=1 loops=1)
-> Gather (actual rows=1 loops=1) -> Gather (actual rows=2 loops=1)
Workers Planned: 1 Workers Planned: 1
Workers Launched: 0 Workers Launched: 1
-> Partial Aggregate (actual rows=1 loops=1) -> Partial Aggregate (actual rows=1 loops=2)
-> Nested Loop (actual rows=0 loops=1) -> Nested Loop (actual rows=0 loops=2)
-> Parallel Seq Scan on lprt_a a (actual rows=100 loops=1) -> Parallel Seq Scan on lprt_a a (actual rows=50 loops=2)
Filter: (a = ANY ('{1,0,0}'::integer[])) Filter: (a = ANY ('{1,0,0}'::integer[]))
Rows Removed by Filter: 2 Rows Removed by Filter: 1
-> Append (actual rows=0 loops=100) -> Append (actual rows=0 loops=100)
-> Index Scan using ab_a1_b1_a_idx on ab_a1_b1 (never executed) -> Index Scan using ab_a1_b1_a_idx on ab_a1_b1 (never executed)
Index Cond: (a = a.a) Index Cond: (a = a.a)

39
src/test/regress/sql/partition_prune.sql
View File

@ -360,6 +360,29 @@ execute ab_q3 (1, 8);
explain (analyze, costs off, summary off, timing off) execute ab_q3 (2, 2); explain (analyze, costs off, summary off, timing off) execute ab_q3 (2, 2);
-- Parallel append -- 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.
create function explain_parallel_append(text, int[]) returns setof text
language plpgsql as
$$
declare
ln text;
args text := string_agg(u::text, ', ') from unnest($2) u;
begin
for ln in
execute format('explain (analyze, costs off, summary off, timing off) execute %s(%s)',
$1, args)
loop
if ln like '%Parallel%' then
ln := regexp_replace(ln, 'loops=\d*', 'loops=N');
end if;
return next ln;
end loop;
end;
$$;
prepare ab_q4 (int, int) as prepare ab_q4 (int, int) as
select avg(a) from ab where a between $1 and $2 and b < 4; select avg(a) from ab where a between $1 and $2 and b < 4;
@ -367,13 +390,8 @@ select avg(a) from ab where a between $1 and $2 and b < 4;
set parallel_setup_cost = 0; set parallel_setup_cost = 0;
set parallel_tuple_cost = 0; set parallel_tuple_cost = 0;
set min_parallel_table_scan_size = 0; set min_parallel_table_scan_size = 0;
-- set this so we get a parallel plan
set max_parallel_workers_per_gather = 2; set max_parallel_workers_per_gather = 2;
-- and zero this so that workers don't destabilize the explain output
set max_parallel_workers = 0;
-- Execute query 5 times to allow choose_custom_plan -- Execute query 5 times to allow choose_custom_plan
-- to start considering a generic plan. -- to start considering a generic plan.
execute ab_q4 (1, 8); execute ab_q4 (1, 8);
@ -381,8 +399,7 @@ execute ab_q4 (1, 8);
execute ab_q4 (1, 8); execute ab_q4 (1, 8);
execute ab_q4 (1, 8); execute ab_q4 (1, 8);
execute ab_q4 (1, 8); execute ab_q4 (1, 8);
select explain_parallel_append('ab_q4', '{2, 2}');
explain (analyze, costs off, summary off, timing off) execute ab_q4 (2, 2);
-- Test run-time pruning with IN lists. -- Test run-time pruning with IN lists.
prepare ab_q5 (int, int, int) as prepare ab_q5 (int, int, int) as
@ -396,12 +413,12 @@ execute ab_q5 (1, 2, 3);
execute ab_q5 (1, 2, 3); execute ab_q5 (1, 2, 3);
execute ab_q5 (1, 2, 3); execute ab_q5 (1, 2, 3);
explain (analyze, costs off, summary off, timing off) execute ab_q5 (1, 1, 1); select explain_parallel_append('ab_q5', '{1, 1, 1}');
explain (analyze, costs off, summary off, timing off) execute ab_q5 (2, 3, 3); select explain_parallel_append('ab_q5', '{2, 3, 3}');
-- Try some params whose values do not belong to any partition. -- Try some params whose values do not belong to any partition.
-- We'll still get a single subplan in this case, but it should not be scanned. -- We'll still get a single subplan in this case, but it should not be scanned.
explain (analyze, costs off, summary off, timing off) execute ab_q5 (33, 44, 55); select explain_parallel_append('ab_q5', '{33, 44, 55}');
-- Test parallel Append with IN list and parameterized nested loops -- Test parallel Append with IN list and parameterized nested loops
create table lprt_a (a int not null); create table lprt_a (a int not null);
@ -434,7 +451,7 @@ execute ab_q6 (1, 2, 3);
execute ab_q6 (1, 2, 3); execute ab_q6 (1, 2, 3);
execute ab_q6 (1, 2, 3); execute ab_q6 (1, 2, 3);
explain (analyze, costs off, summary off, timing off) execute ab_q6 (0, 0, 1); select explain_parallel_append('ab_q6', '{0, 0, 1}');
insert into lprt_a values(3),(3); insert into lprt_a values(3),(3);