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|
DO $$
DECLARE
v_version numeric;
BEGIN
SELECT substring(setting from '\d+')::numeric INTO v_version FROM pg_settings WHERE name = 'server_version';
-- GUCs common for all versions
PERFORM set_config('extra_float_digits', '0', false);
PERFORM set_config('parallel_setup_cost', '0', false);
PERFORM set_config('parallel_tuple_cost', '0', false);
PERFORM set_config('max_parallel_workers_per_gather', '2', false);
-- 9.6 used somewhat different GUC name for relation size
IF v_version < 10 THEN
PERFORM set_config('min_parallel_relation_size', '1kB', false);
ELSE
PERFORM set_config('min_parallel_table_scan_size', '1kB', false);
END IF;
-- in 14 disable Memoize nodes, to make explain more consistent
IF v_version >= 14 THEN
PERFORM set_config('enable_memoize', 'off', false);
END IF;
END;
$$ LANGUAGE plpgsql;
-- test parallel query
DROP TABLE t;
CREATE TABLE t (v double precision, c int, d int);
INSERT INTO t SELECT 1000 * random(), 1 + mod(i,7), mod(i,113) FROM generate_series(1,100000) s(i);
ANALYZE t;
CREATE TABLE t2 (d tdigest);
INSERT INTO t2 SELECT tdigest(v, 100) FROM t GROUP BY d;
ANALYZE t2;
-- individual values
EXPLAIN (COSTS OFF)
WITH x AS (SELECT percentile_disc(0.95) WITHIN GROUP (ORDER BY v) AS p FROM t)
SELECT
0.95,
abs(a - b) / 1000 < 0.01
FROM (
SELECT
(SELECT p FROM x) AS a,
tdigest_percentile(v, 100, 0.95) AS b
FROM t) foo;
QUERY PLAN
------------------------------------------------
Subquery Scan on foo
CTE x
-> Aggregate
-> Gather
Workers Planned: 2
-> Parallel Seq Scan on t t_1
-> Finalize Aggregate
InitPlan 2 (returns $2)
-> CTE Scan on x
-> Gather
Workers Planned: 2
-> Partial Aggregate
-> Parallel Seq Scan on t
(13 rows)
WITH x AS (SELECT percentile_disc(0.95) WITHIN GROUP (ORDER BY v) AS p FROM t)
SELECT
0.95,
abs(a - b) / 1000 < 0.01
FROM (
SELECT
(SELECT p FROM x) AS a,
tdigest_percentile(v, 100, 0.95) AS b
FROM t) foo;
?column? | ?column?
----------+----------
0.95 | t
(1 row)
EXPLAIN (COSTS OFF)
SELECT
950,
abs(a - b) < 0.01
FROM (
SELECT
0.95 AS a,
tdigest_percentile_of(v, 100, 950) AS b
FROM t) foo;
QUERY PLAN
------------------------------------------------
Subquery Scan on foo
-> Finalize Aggregate
-> Gather
Workers Planned: 2
-> Partial Aggregate
-> Parallel Seq Scan on t
(6 rows)
SELECT
950,
abs(a - b) < 0.01
FROM (
SELECT
0.95 AS a,
tdigest_percentile_of(v, 100, 950) AS b
FROM t) foo;
?column? | ?column?
----------+----------
950 | t
(1 row)
EXPLAIN (COSTS OFF)
WITH x AS (SELECT percentile_disc(0.95) WITHIN GROUP (ORDER BY v) AS p FROM t)
SELECT
0.95,
abs(a - b) / 1000 < 0.01
FROM (
SELECT
(SELECT p FROM x) AS a,
tdigest_percentile(d, 0.95) AS b
FROM t2) foo;
QUERY PLAN
-------------------------------------------------
Subquery Scan on foo
CTE x
-> Aggregate
-> Gather
Workers Planned: 2
-> Parallel Seq Scan on t
-> Finalize Aggregate
InitPlan 2 (returns $2)
-> CTE Scan on x
-> Gather
Workers Planned: 2
-> Partial Aggregate
-> Parallel Seq Scan on t2
(13 rows)
WITH x AS (SELECT percentile_disc(0.95) WITHIN GROUP (ORDER BY v) AS p FROM t)
SELECT
0.95,
abs(a - b) / 1000 < 0.01
FROM (
SELECT
(SELECT p FROM x) AS a,
tdigest_percentile(d, 0.95) AS b
FROM t2) foo;
?column? | ?column?
----------+----------
0.95 | t
(1 row)
EXPLAIN (COSTS OFF)
SELECT
950,
abs(a - b) < 0.01
FROM (
SELECT
0.95 AS a,
tdigest_percentile_of(d, 950) AS b
FROM t2) foo;
QUERY PLAN
-------------------------------------------------
Subquery Scan on foo
-> Finalize Aggregate
-> Gather
Workers Planned: 2
-> Partial Aggregate
-> Parallel Seq Scan on t2
(6 rows)
SELECT
950,
abs(a - b) < 0.01
FROM (
SELECT
0.95 AS a,
tdigest_percentile_of(d, 950) AS b
FROM t2) foo;
?column? | ?column?
----------+----------
950 | t
(1 row)
-- array of percentiles / values
EXPLAIN (COSTS OFF)
WITH x AS (SELECT percentile_disc(ARRAY[0.0, 0.95, 0.99, 1.0]) WITHIN GROUP (ORDER BY v) AS p FROM t)
SELECT
p,
abs(a - b) / 1000 < 0.01
FROM (
SELECT
unnest(ARRAY[0.0, 0.95, 0.99, 1.0]) p,
unnest((SELECT p FROM x)) AS a,
unnest(tdigest_percentile(v, 100, ARRAY[0.0, 0.95, 0.99, 1.0])) AS b
FROM t) foo;
QUERY PLAN
------------------------------------------------------
Subquery Scan on foo
CTE x
-> Aggregate
-> Gather
Workers Planned: 2
-> Parallel Seq Scan on t t_1
-> ProjectSet
InitPlan 2 (returns $2)
-> CTE Scan on x
-> Finalize Aggregate
-> Gather
Workers Planned: 2
-> Partial Aggregate
-> Parallel Seq Scan on t
(14 rows)
WITH x AS (SELECT percentile_disc(ARRAY[0.0, 0.95, 0.99, 1.0]) WITHIN GROUP (ORDER BY v) AS p FROM t)
SELECT
p,
abs(a - b) / 1000 < 0.01
FROM (
SELECT
unnest(ARRAY[0.0, 0.95, 0.99, 1.0]) p,
unnest((SELECT p FROM x)) AS a,
unnest(tdigest_percentile(v, 100, ARRAY[0.0, 0.95, 0.99, 1.0])) AS b
FROM t) foo;
p | ?column?
------+----------
0.0 | t
0.95 | t
0.99 | t
1.0 | t
(4 rows)
EXPLAIN (COSTS OFF)
WITH x AS (SELECT array_agg((SELECT percent_rank(f) WITHIN GROUP (ORDER BY v) FROM t)) AS p FROM unnest(ARRAY[950, 990]) f)
SELECT
p,
abs(a - b) < 0.01
FROM (
SELECT
unnest(ARRAY[950, 990]) AS p,
unnest((SELECT p FROM x)) AS a,
unnest(tdigest_percentile_of(v, 100, ARRAY[950, 990])) AS b
FROM t) foo;
QUERY PLAN
--------------------------------------------------------
Subquery Scan on foo
CTE x
-> Aggregate
-> Function Scan on unnest f
SubPlan 1
-> Aggregate
-> Gather
Workers Planned: 2
-> Parallel Seq Scan on t t_1
-> ProjectSet
InitPlan 3 (returns $3)
-> CTE Scan on x
-> Finalize Aggregate
-> Gather
Workers Planned: 2
-> Partial Aggregate
-> Parallel Seq Scan on t
(17 rows)
WITH x AS (SELECT array_agg((SELECT percent_rank(f) WITHIN GROUP (ORDER BY v) FROM t)) AS p FROM unnest(ARRAY[950, 990]) f)
SELECT
p,
abs(a - b) < 0.01
FROM (
SELECT
unnest(ARRAY[950, 990]) AS p,
unnest((SELECT p FROM x)) AS a,
unnest(tdigest_percentile_of(v, 100, ARRAY[950, 990])) AS b
FROM t) foo;
p | ?column?
-----+----------
950 | t
990 | t
(2 rows)
EXPLAIN (COSTS OFF)
WITH x AS (SELECT percentile_disc(ARRAY[0.0, 0.95, 0.99, 1.0]) WITHIN GROUP (ORDER BY v) AS p FROM t)
SELECT
p,
abs(a - b) / 1000 < 0.01
FROM (
SELECT
unnest(ARRAY[0.0, 0.95, 0.99, 1.0]) p,
unnest((SELECT p FROM x)) AS a,
unnest(tdigest_percentile(d, ARRAY[0.0, 0.95, 0.99, 1.0])) AS b
FROM t2) foo;
QUERY PLAN
-------------------------------------------------------
Subquery Scan on foo
CTE x
-> Aggregate
-> Gather
Workers Planned: 2
-> Parallel Seq Scan on t
-> ProjectSet
InitPlan 2 (returns $2)
-> CTE Scan on x
-> Finalize Aggregate
-> Gather
Workers Planned: 2
-> Partial Aggregate
-> Parallel Seq Scan on t2
(14 rows)
WITH x AS (SELECT percentile_disc(ARRAY[0.0, 0.95, 0.99, 1.0]) WITHIN GROUP (ORDER BY v) AS p FROM t)
SELECT
p,
abs(a - b) / 1000 < 0.01
FROM (
SELECT
unnest(ARRAY[0.0, 0.95, 0.99, 1.0]) p,
unnest((SELECT p FROM x)) AS a,
unnest(tdigest_percentile(d, ARRAY[0.0, 0.95, 0.99, 1.0])) AS b
FROM t2) foo;
p | ?column?
------+----------
0.0 | t
0.95 | t
0.99 | t
1.0 | t
(4 rows)
EXPLAIN (COSTS OFF)
WITH x AS (SELECT array_agg((SELECT percent_rank(f) WITHIN GROUP (ORDER BY v) FROM t)) AS p FROM unnest(ARRAY[950, 990]) f)
SELECT
p,
abs(a - b) < 0.01
FROM (
SELECT
unnest(ARRAY[950, 990]) AS p,
unnest((SELECT p FROM x)) AS a,
unnest(tdigest_percentile_of(d, ARRAY[950, 990])) AS b
FROM t2) foo;
QUERY PLAN
-------------------------------------------------------
Subquery Scan on foo
CTE x
-> Aggregate
-> Function Scan on unnest f
SubPlan 1
-> Aggregate
-> Gather
Workers Planned: 2
-> Parallel Seq Scan on t
-> ProjectSet
InitPlan 3 (returns $3)
-> CTE Scan on x
-> Finalize Aggregate
-> Gather
Workers Planned: 2
-> Partial Aggregate
-> Parallel Seq Scan on t2
(17 rows)
WITH x AS (SELECT array_agg((SELECT percent_rank(f) WITHIN GROUP (ORDER BY v) FROM t)) AS p FROM unnest(ARRAY[950, 990]) f)
SELECT
p,
abs(a - b) < 0.01
FROM (
SELECT
unnest(ARRAY[950, 990]) AS p,
unnest((SELECT p FROM x)) AS a,
unnest(tdigest_percentile_of(d, ARRAY[950, 990])) AS b
FROM t2) foo;
p | ?column?
-----+----------
950 | t
990 | t
(2 rows)
|
