mirror of
https://github.com/timescale/timescaledb.git
synced 2025-05-21 21:21:22 +08:00
36bff37daf
PostgreSQL will produce plans where a parallel append has children that are not partial paths. This patch adds support for those plans to ChunkAppend.
120 lines
4.3 KiB
MySQL
120 lines
4.3 KiB
MySQL
-- This file and its contents are licensed under the Apache License 2.0.
|
|
-- Please see the included NOTICE for copyright information and
|
|
-- LICENSE-APACHE for a copy of the license.
|
|
|
|
--parallel queries require big-ish tables so collect them all here
|
|
--so that we need to generate queries only once.
|
|
|
|
-- look at postgres version to decide whether we run with analyze or without
|
|
SELECT
|
|
CASE WHEN current_setting('server_version_num')::int >= 100000
|
|
THEN 'EXPLAIN (analyze, costs off, timing off, summary off)'
|
|
ELSE 'EXPLAIN (costs off)'
|
|
END AS "PREFIX",
|
|
'EXPLAIN (costs off)' AS "PREFIX_NO_ANALYZE"
|
|
\gset
|
|
|
|
\set CHUNK1 _timescaledb_internal._hyper_1_1_chunk
|
|
\set CHUNK2 _timescaledb_internal._hyper_1_2_chunk
|
|
|
|
CREATE TABLE test (i int, j double precision, ts timestamp);
|
|
SELECT create_hypertable('test','i',chunk_time_interval:=500000);
|
|
--has to be big enough to force at least 2 workers below.
|
|
INSERT INTO test SELECT x, x+0.1, _timescaledb_internal.to_timestamp(x*1000) FROM generate_series(0,1000000-1) AS x;
|
|
|
|
ANALYZE test;
|
|
|
|
SET work_mem TO '50MB';
|
|
SET force_parallel_mode = 'on';
|
|
SET max_parallel_workers_per_gather = 4;
|
|
|
|
EXPLAIN (costs off) SELECT first(i, j) FROM "test";
|
|
SELECT first(i, j) FROM "test";
|
|
|
|
EXPLAIN (costs off) SELECT last(i, j) FROM "test";
|
|
SELECT last(i, j) FROM "test";
|
|
|
|
EXPLAIN (costs off) SELECT time_bucket('1 second', ts) sec, last(i, j)
|
|
FROM "test"
|
|
GROUP BY sec
|
|
ORDER BY sec
|
|
LIMIT 5;
|
|
|
|
-- test single copy parallel plan with parallel chunk append
|
|
-- output with analyze is not stable because it depends on worker assignment
|
|
:PREFIX_NO_ANALYZE SELECT time_bucket('1 second', ts) sec, last(i, j)
|
|
FROM "test"
|
|
WHERE length(version()) > 0
|
|
GROUP BY sec
|
|
ORDER BY sec
|
|
LIMIT 5;
|
|
|
|
SELECT time_bucket('1 second', ts) sec, last(i, j)
|
|
FROM "test"
|
|
GROUP BY sec
|
|
ORDER BY sec
|
|
LIMIT 5;
|
|
|
|
--test variants of histogram
|
|
EXPLAIN (costs off) SELECT histogram(i, 1, 1000000, 2) FROM "test";
|
|
SELECT histogram(i, 1, 1000000, 2) FROM "test";
|
|
|
|
EXPLAIN (costs off) SELECT histogram(i, 1,1000001,10) FROM "test";
|
|
SELECT histogram(i, 1, 1000001, 10) FROM "test";
|
|
|
|
EXPLAIN (costs off) SELECT histogram(i, 0,100000,5) FROM "test";
|
|
SELECT histogram(i, 0, 100000, 5) FROM "test";
|
|
|
|
EXPLAIN (costs off) SELECT histogram(i, 10,100000,5) FROM "test";
|
|
SELECT histogram(i, 10, 100000, 5) FROM "test";
|
|
|
|
-- test parallel ChunkAppend
|
|
:PREFIX SELECT i FROM "test" WHERE length(version()) > 0;
|
|
|
|
-- test worker assignment
|
|
-- first chunk should have 1 worker and second chunk should have 2
|
|
SET max_parallel_workers_per_gather TO 2;
|
|
:PREFIX SELECT count(*) FROM "test" WHERE i >= 400000 AND length(version()) > 0;
|
|
SELECT count(*) FROM "test" WHERE i >= 400000 AND length(version()) > 0;
|
|
|
|
-- test worker assignment
|
|
-- first chunk should have 2 worker and second chunk should have 1
|
|
:PREFIX SELECT count(*) FROM "test" WHERE i < 600000 AND length(version()) > 0;
|
|
SELECT count(*) FROM "test" WHERE i < 600000 AND length(version()) > 0;
|
|
|
|
-- test ChunkAppend with # workers < # childs
|
|
SET max_parallel_workers_per_gather TO 1;
|
|
:PREFIX SELECT count(*) FROM "test" WHERE length(version()) > 0;
|
|
SELECT count(*) FROM "test" WHERE length(version()) > 0;
|
|
|
|
-- test ChunkAppend with # workers > # childs
|
|
SET max_parallel_workers_per_gather TO 2;
|
|
:PREFIX SELECT count(*) FROM "test" WHERE i >= 500000 AND length(version()) > 0;
|
|
SELECT count(*) FROM "test" WHERE i >= 500000 AND length(version()) > 0;
|
|
|
|
RESET max_parallel_workers_per_gather;
|
|
|
|
-- test partial and non-partial plans
|
|
-- these will not be parallel on PG < 11
|
|
ALTER TABLE :CHUNK1 SET (parallel_workers=0);
|
|
ALTER TABLE :CHUNK2 SET (parallel_workers=2);
|
|
:PREFIX SELECT count(*) FROM "test" WHERE i > 400000 AND length(version()) > 0;
|
|
|
|
ALTER TABLE :CHUNK1 SET (parallel_workers=2);
|
|
ALTER TABLE :CHUNK2 SET (parallel_workers=0);
|
|
:PREFIX SELECT count(*) FROM "test" WHERE i < 600000 AND length(version()) > 0;
|
|
|
|
ALTER TABLE :CHUNK1 RESET (parallel_workers);
|
|
ALTER TABLE :CHUNK2 RESET (parallel_workers);
|
|
|
|
-- now() is not marked parallel safe in PostgreSQL < 12 so using now()
|
|
-- in a query will prevent parallelism but CURRENT_TIMESTAMP and
|
|
-- transaction_timestamp() are marked parallel safe
|
|
:PREFIX SELECT i FROM "test" WHERE ts < CURRENT_TIMESTAMP;
|
|
|
|
:PREFIX SELECT i FROM "test" WHERE ts < transaction_timestamp();
|
|
|
|
-- this won't be parallel query because now() is parallel restricted in PG < 12
|
|
:PREFIX SELECT i FROM "test" WHERE ts < now();
|
|
|