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https://github.com/postgres/postgres.git
synced 2025-04-22 23:02:54 +03:00
Restore partition_prune's usage of parallel workers
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
parent
b15e8f71db
commit
47c91b5599
@ -1748,16 +1748,34 @@ explain (analyze, costs off, summary off, timing off) execute ab_q3 (2, 2);
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(10 rows)
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-- Parallel append
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-- Suppress the number of loops each parallel node runs for. This is because
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-- more than one worker may run the same parallel node if timing conditions
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-- are just right, which destabilizes the test.
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create function explain_parallel_append(text, int[]) returns setof text
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language plpgsql as
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$$
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declare
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ln text;
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args text := string_agg(u::text, ', ') from unnest($2) u;
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begin
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for ln in
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execute format('explain (analyze, costs off, summary off, timing off) execute %s(%s)',
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$1, args)
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loop
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if ln like '%Parallel%' then
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ln := regexp_replace(ln, 'loops=\d*', 'loops=N');
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end if;
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return next ln;
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end loop;
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end;
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$$;
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prepare ab_q4 (int, int) as
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select avg(a) from ab where a between $1 and $2 and b < 4;
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-- Encourage use of parallel plans
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set parallel_setup_cost = 0;
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set parallel_tuple_cost = 0;
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set min_parallel_table_scan_size = 0;
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-- set this so we get a parallel plan
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set max_parallel_workers_per_gather = 2;
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-- and zero this so that workers don't destabilize the explain output
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set max_parallel_workers = 0;
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-- Execute query 5 times to allow choose_custom_plan
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-- to start considering a generic plan.
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execute ab_q4 (1, 8);
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@ -1790,21 +1808,21 @@ execute ab_q4 (1, 8);
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(1 row)
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explain (analyze, costs off, summary off, timing off) execute ab_q4 (2, 2);
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QUERY PLAN
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select explain_parallel_append('ab_q4', '{2, 2}');
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explain_parallel_append
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-------------------------------------------------------------------------------
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Finalize Aggregate (actual rows=1 loops=1)
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-> Gather (actual rows=1 loops=1)
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-> Gather (actual rows=3 loops=1)
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Workers Planned: 2
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Workers Launched: 0
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-> Partial Aggregate (actual rows=1 loops=1)
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-> Parallel Append (actual rows=0 loops=1)
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Workers Launched: 2
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-> Partial Aggregate (actual rows=1 loops=3)
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-> Parallel Append (actual rows=0 loops=N)
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Subplans Removed: 6
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-> Parallel Seq Scan on ab_a2_b1 (actual rows=0 loops=1)
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-> Parallel Seq Scan on ab_a2_b1 (actual rows=0 loops=N)
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Filter: ((a >= $1) AND (a <= $2) AND (b < 4))
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-> Parallel Seq Scan on ab_a2_b2 (actual rows=0 loops=1)
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-> Parallel Seq Scan on ab_a2_b2 (actual rows=0 loops=N)
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Filter: ((a >= $1) AND (a <= $2) AND (b < 4))
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-> Parallel Seq Scan on ab_a2_b3 (actual rows=0 loops=1)
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-> Parallel Seq Scan on ab_a2_b3 (actual rows=0 loops=N)
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Filter: ((a >= $1) AND (a <= $2) AND (b < 4))
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(13 rows)
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@ -1843,59 +1861,59 @@ execute ab_q5 (1, 2, 3);
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(1 row)
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explain (analyze, costs off, summary off, timing off) execute ab_q5 (1, 1, 1);
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QUERY PLAN
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select explain_parallel_append('ab_q5', '{1, 1, 1}');
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explain_parallel_append
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-------------------------------------------------------------------------------
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Finalize Aggregate (actual rows=1 loops=1)
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-> Gather (actual rows=1 loops=1)
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-> Gather (actual rows=3 loops=1)
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Workers Planned: 2
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Workers Launched: 0
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-> Partial Aggregate (actual rows=1 loops=1)
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-> Parallel Append (actual rows=0 loops=1)
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Workers Launched: 2
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-> Partial Aggregate (actual rows=1 loops=3)
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-> Parallel Append (actual rows=0 loops=N)
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Subplans Removed: 6
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-> Parallel Seq Scan on ab_a1_b1 (actual rows=0 loops=1)
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-> Parallel Seq Scan on ab_a1_b1 (actual rows=0 loops=N)
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Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
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-> Parallel Seq Scan on ab_a1_b2 (actual rows=0 loops=1)
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-> Parallel Seq Scan on ab_a1_b2 (actual rows=0 loops=N)
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Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
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-> Parallel Seq Scan on ab_a1_b3 (actual rows=0 loops=1)
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-> Parallel Seq Scan on ab_a1_b3 (actual rows=0 loops=N)
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Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
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(13 rows)
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explain (analyze, costs off, summary off, timing off) execute ab_q5 (2, 3, 3);
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QUERY PLAN
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select explain_parallel_append('ab_q5', '{2, 3, 3}');
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explain_parallel_append
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-------------------------------------------------------------------------------
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Finalize Aggregate (actual rows=1 loops=1)
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-> Gather (actual rows=1 loops=1)
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-> Gather (actual rows=3 loops=1)
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Workers Planned: 2
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Workers Launched: 0
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-> Partial Aggregate (actual rows=1 loops=1)
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-> Parallel Append (actual rows=0 loops=1)
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Workers Launched: 2
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-> Partial Aggregate (actual rows=1 loops=3)
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-> Parallel Append (actual rows=0 loops=N)
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Subplans Removed: 3
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-> Parallel Seq Scan on ab_a2_b1 (actual rows=0 loops=1)
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-> Parallel Seq Scan on ab_a2_b1 (actual rows=0 loops=N)
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Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
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-> Parallel Seq Scan on ab_a2_b2 (actual rows=0 loops=1)
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-> Parallel Seq Scan on ab_a2_b2 (actual rows=0 loops=N)
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Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
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-> Parallel Seq Scan on ab_a2_b3 (actual rows=0 loops=1)
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-> Parallel Seq Scan on ab_a2_b3 (actual rows=0 loops=N)
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Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
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-> Parallel Seq Scan on ab_a3_b1 (actual rows=0 loops=1)
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-> Parallel Seq Scan on ab_a3_b1 (actual rows=0 loops=N)
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Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
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-> Parallel Seq Scan on ab_a3_b2 (actual rows=0 loops=1)
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-> Parallel Seq Scan on ab_a3_b2 (actual rows=0 loops=N)
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Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
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-> Parallel Seq Scan on ab_a3_b3 (actual rows=0 loops=1)
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-> Parallel Seq Scan on ab_a3_b3 (actual rows=0 loops=N)
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Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
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(19 rows)
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-- Try some params whose values do not belong to any partition.
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-- We'll still get a single subplan in this case, but it should not be scanned.
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explain (analyze, costs off, summary off, timing off) execute ab_q5 (33, 44, 55);
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QUERY PLAN
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select explain_parallel_append('ab_q5', '{33, 44, 55}');
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explain_parallel_append
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-------------------------------------------------------------------------------
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Finalize Aggregate (actual rows=1 loops=1)
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-> Gather (actual rows=1 loops=1)
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-> Gather (actual rows=3 loops=1)
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Workers Planned: 2
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Workers Launched: 0
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-> Partial Aggregate (actual rows=1 loops=1)
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-> Parallel Append (actual rows=0 loops=1)
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Workers Launched: 2
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-> Partial Aggregate (actual rows=1 loops=3)
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-> Parallel Append (actual rows=0 loops=N)
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Subplans Removed: 8
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-> Parallel Seq Scan on ab_a1_b1 (never executed)
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Filter: ((b < 4) AND (a = ANY (ARRAY[$1, $2, $3])))
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@ -1951,16 +1969,16 @@ execute ab_q6 (1, 2, 3);
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(1 row)
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explain (analyze, costs off, summary off, timing off) execute ab_q6 (0, 0, 1);
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QUERY PLAN
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select explain_parallel_append('ab_q6', '{0, 0, 1}');
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explain_parallel_append
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---------------------------------------------------------------------------------------------------
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Finalize Aggregate (actual rows=1 loops=1)
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-> Gather (actual rows=1 loops=1)
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-> Gather (actual rows=2 loops=1)
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Workers Planned: 1
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Workers Launched: 0
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-> Partial Aggregate (actual rows=1 loops=1)
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-> Nested Loop (actual rows=0 loops=1)
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-> Parallel Seq Scan on lprt_a a (actual rows=102 loops=1)
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Workers Launched: 1
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-> Partial Aggregate (actual rows=1 loops=2)
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-> Nested Loop (actual rows=0 loops=2)
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-> Parallel Seq Scan on lprt_a a (actual rows=51 loops=N)
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Filter: (a = ANY ('{0,0,1}'::integer[]))
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-> Append (actual rows=0 loops=102)
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-> Index Scan using ab_a1_b1_a_idx on ab_a1_b1 (actual rows=0 loops=2)
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@ -1988,12 +2006,12 @@ explain (analyze, costs off, summary off, timing off) execute ab_q6 (1, 0, 3);
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QUERY PLAN
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---------------------------------------------------------------------------------------------------
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Finalize Aggregate (actual rows=1 loops=1)
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-> Gather (actual rows=1 loops=1)
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-> Gather (actual rows=2 loops=1)
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Workers Planned: 1
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Workers Launched: 0
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-> Partial Aggregate (actual rows=1 loops=1)
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-> Nested Loop (actual rows=0 loops=1)
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-> Parallel Seq Scan on lprt_a a (actual rows=104 loops=1)
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Workers Launched: 1
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-> Partial Aggregate (actual rows=1 loops=2)
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-> Nested Loop (actual rows=0 loops=2)
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-> Parallel Seq Scan on lprt_a a (actual rows=52 loops=2)
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Filter: (a = ANY ('{1,0,3}'::integer[]))
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-> Append (actual rows=0 loops=104)
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-> Index Scan using ab_a1_b1_a_idx on ab_a1_b1 (actual rows=0 loops=2)
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@ -2020,14 +2038,14 @@ explain (analyze, costs off, summary off, timing off) execute ab_q6 (1, 0, 0);
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QUERY PLAN
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---------------------------------------------------------------------------------------------------
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Finalize Aggregate (actual rows=1 loops=1)
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-> Gather (actual rows=1 loops=1)
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-> Gather (actual rows=2 loops=1)
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Workers Planned: 1
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Workers Launched: 0
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-> Partial Aggregate (actual rows=1 loops=1)
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-> Nested Loop (actual rows=0 loops=1)
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-> Parallel Seq Scan on lprt_a a (actual rows=102 loops=1)
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Workers Launched: 1
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-> Partial Aggregate (actual rows=1 loops=2)
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-> Nested Loop (actual rows=0 loops=2)
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-> Parallel Seq Scan on lprt_a a (actual rows=51 loops=2)
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Filter: (a = ANY ('{1,0,0}'::integer[]))
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Rows Removed by Filter: 2
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Rows Removed by Filter: 1
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-> Append (actual rows=0 loops=102)
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-> Index Scan using ab_a1_b1_a_idx on ab_a1_b1 (actual rows=0 loops=2)
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Index Cond: (a = a.a)
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@ -2054,14 +2072,14 @@ explain (analyze, costs off, summary off, timing off) execute ab_q6 (1, 0, 0);
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QUERY PLAN
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--------------------------------------------------------------------------------------------
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Finalize Aggregate (actual rows=1 loops=1)
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-> Gather (actual rows=1 loops=1)
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-> Gather (actual rows=2 loops=1)
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Workers Planned: 1
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Workers Launched: 0
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-> Partial Aggregate (actual rows=1 loops=1)
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-> Nested Loop (actual rows=0 loops=1)
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-> Parallel Seq Scan on lprt_a a (actual rows=100 loops=1)
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Workers Launched: 1
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-> Partial Aggregate (actual rows=1 loops=2)
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-> Nested Loop (actual rows=0 loops=2)
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-> Parallel Seq Scan on lprt_a a (actual rows=50 loops=2)
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Filter: (a = ANY ('{1,0,0}'::integer[]))
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Rows Removed by Filter: 2
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Rows Removed by Filter: 1
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-> Append (actual rows=0 loops=100)
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-> Index Scan using ab_a1_b1_a_idx on ab_a1_b1 (never executed)
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Index Cond: (a = a.a)
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@ -360,6 +360,29 @@ execute ab_q3 (1, 8);
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explain (analyze, costs off, summary off, timing off) execute ab_q3 (2, 2);
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-- Parallel append
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-- Suppress the number of loops each parallel node runs for. This is because
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-- more than one worker may run the same parallel node if timing conditions
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-- are just right, which destabilizes the test.
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create function explain_parallel_append(text, int[]) returns setof text
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language plpgsql as
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$$
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declare
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ln text;
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args text := string_agg(u::text, ', ') from unnest($2) u;
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begin
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for ln in
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execute format('explain (analyze, costs off, summary off, timing off) execute %s(%s)',
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$1, args)
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loop
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if ln like '%Parallel%' then
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ln := regexp_replace(ln, 'loops=\d*', 'loops=N');
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end if;
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return next ln;
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end loop;
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end;
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$$;
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prepare ab_q4 (int, int) as
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select avg(a) from ab where a between $1 and $2 and b < 4;
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@ -367,13 +390,8 @@ select avg(a) from ab where a between $1 and $2 and b < 4;
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set parallel_setup_cost = 0;
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set parallel_tuple_cost = 0;
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set min_parallel_table_scan_size = 0;
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-- set this so we get a parallel plan
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set max_parallel_workers_per_gather = 2;
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-- and zero this so that workers don't destabilize the explain output
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set max_parallel_workers = 0;
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-- Execute query 5 times to allow choose_custom_plan
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-- to start considering a generic plan.
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execute ab_q4 (1, 8);
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@ -381,8 +399,7 @@ execute ab_q4 (1, 8);
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execute ab_q4 (1, 8);
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execute ab_q4 (1, 8);
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execute ab_q4 (1, 8);
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explain (analyze, costs off, summary off, timing off) execute ab_q4 (2, 2);
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select explain_parallel_append('ab_q4', '{2, 2}');
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-- Test run-time pruning with IN lists.
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prepare ab_q5 (int, int, int) as
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@ -396,12 +413,12 @@ execute ab_q5 (1, 2, 3);
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execute ab_q5 (1, 2, 3);
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execute ab_q5 (1, 2, 3);
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explain (analyze, costs off, summary off, timing off) execute ab_q5 (1, 1, 1);
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explain (analyze, costs off, summary off, timing off) execute ab_q5 (2, 3, 3);
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select explain_parallel_append('ab_q5', '{1, 1, 1}');
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select explain_parallel_append('ab_q5', '{2, 3, 3}');
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-- Try some params whose values do not belong to any partition.
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-- We'll still get a single subplan in this case, but it should not be scanned.
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explain (analyze, costs off, summary off, timing off) execute ab_q5 (33, 44, 55);
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select explain_parallel_append('ab_q5', '{33, 44, 55}');
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-- Test parallel Append with IN list and parameterized nested loops
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create table lprt_a (a int not null);
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@ -434,7 +451,7 @@ execute ab_q6 (1, 2, 3);
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execute ab_q6 (1, 2, 3);
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execute ab_q6 (1, 2, 3);
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explain (analyze, costs off, summary off, timing off) execute ab_q6 (0, 0, 1);
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select explain_parallel_append('ab_q6', '{0, 0, 1}');
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insert into lprt_a values(3),(3);
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