LOAD 'pg_hint_plan'; ALTER SYSTEM SET session_preload_libraries TO 'pg_hint_plan'; SET pg_hint_plan.enable_hint TO on; SET pg_hint_plan.debug_print TO on; SET client_min_messages TO LOG; CREATE TABLE s1.tl (a int); INSERT INTO s1.tl (SELECT a FROM generate_series(0, 100000) a); -- Queries on ordinary tables EXPLAIN (COSTS false) SELECT * FROM s1.t1; QUERY PLAN ---------------- Seq Scan on t1 (1 row) SET parallel_setup_cost to 0; SET parallel_tuple_cost to 0; SET min_parallel_relation_size to 0; /*+Parallel(t1 10)*/ EXPLAIN (COSTS false) SELECT * FROM s1.t1; LOG: pg_hint_plan: used hint: Parallel(t1 10 soft) not used hint: duplication hint: error hint: QUERY PLAN ------------------------------- Gather Workers Planned: 2 -> Parallel Seq Scan on t1 (3 rows) /*+Parallel(t1 10 soft)*/ EXPLAIN (COSTS false) SELECT * FROM s1.t1; LOG: pg_hint_plan: used hint: Parallel(t1 10 soft) not used hint: duplication hint: error hint: QUERY PLAN ------------------------------- Gather Workers Planned: 2 -> Parallel Seq Scan on t1 (3 rows) SET parallel_setup_cost to DEFAULT; SET parallel_tuple_cost to DEFAULT; SET min_parallel_relation_size to DEFAULT; /*+Parallel(t1 10 hard)*/ EXPLAIN (COSTS false) SELECT * FROM s1.t1; LOG: pg_hint_plan: used hint: Parallel(t1 10 hard) not used hint: duplication hint: error hint: QUERY PLAN ------------------------------- Gather Workers Planned: 10 -> Parallel Seq Scan on t1 (3 rows) -- Queries on inheritance tables SET parallel_setup_cost to 0; SET parallel_tuple_cost to 0; SET min_parallel_relation_size to 0; /*+Parallel(p1 10)*/ EXPLAIN (COSTS false) SELECT * FROM p1; LOG: pg_hint_plan: used hint: Parallel(p1 10 soft) not used hint: duplication hint: error hint: QUERY PLAN ------------------------------------------- Gather Workers Planned: 1 -> Append -> Parallel Seq Scan on p1 -> Parallel Seq Scan on p1_c1 -> Parallel Seq Scan on p1_c2 -> Parallel Seq Scan on p1_c3 -> Parallel Seq Scan on p1_c4 -> Parallel Seq Scan on p1_c1_c1 -> Parallel Seq Scan on p1_c1_c2 -> Parallel Seq Scan on p1_c3_c1 -> Parallel Seq Scan on p1_c3_c2 (12 rows) SET parallel_setup_cost to DEFAULT; SET parallel_tuple_cost to DEFAULT; SET min_parallel_relation_size to DEFAULT; /*+Parallel(p1 10 hard)*/ EXPLAIN (COSTS false) SELECT * FROM p1; LOG: pg_hint_plan: used hint: Parallel(p1 10 hard) not used hint: duplication hint: error hint: QUERY PLAN ------------------------------------------- Gather Workers Planned: 10 -> Append -> Parallel Seq Scan on p1 -> Parallel Seq Scan on p1_c1 -> Parallel Seq Scan on p1_c2 -> Parallel Seq Scan on p1_c3 -> Parallel Seq Scan on p1_c4 -> Parallel Seq Scan on p1_c1_c1 -> Parallel Seq Scan on p1_c1_c2 -> Parallel Seq Scan on p1_c3_c1 -> Parallel Seq Scan on p1_c3_c2 (12 rows) -- hinting on children don't work but enables parallel /*+Parallel(p1_c1 10 hard)*/ EXPLAIN (COSTS false) SELECT * FROM p1; LOG: pg_hint_plan: used hint: not used hint: Parallel(p1_c1 10 hard) duplication hint: error hint: QUERY PLAN ------------------------------------------- Gather Workers Planned: 1 -> Append -> Parallel Seq Scan on p1 -> Parallel Seq Scan on p1_c1 -> Parallel Seq Scan on p1_c2 -> Parallel Seq Scan on p1_c3 -> Parallel Seq Scan on p1_c4 -> Parallel Seq Scan on p1_c1_c1 -> Parallel Seq Scan on p1_c1_c2 -> Parallel Seq Scan on p1_c3_c1 -> Parallel Seq Scan on p1_c3_c2 (12 rows) -- Joins EXPLAIN (COSTS false) SELECT * FROM p1_c1 join p2_c1 on p1_c1.id = p2_c1.id; QUERY PLAN ---------------------------------------- Hash Join Hash Cond: (p1_c1.id = p2_c1.id) -> Append -> Seq Scan on p1_c1 -> Seq Scan on p1_c1_c1 -> Seq Scan on p1_c1_c2 -> Hash -> Append -> Seq Scan on p2_c1 -> Seq Scan on p2_c1_c1 -> Seq Scan on p2_c1_c2 (11 rows) /*+Parallel(p1_c1 10 hard)*/ EXPLAIN (COSTS false) SELECT * FROM p1_c1 join p2_c1 on p1_c1.id = p2_c1.id; LOG: pg_hint_plan: used hint: Parallel(p1_c1 10 hard) not used hint: duplication hint: error hint: QUERY PLAN ------------------------------------------------------- Hash Join Hash Cond: (p1_c1.id = p2_c1.id) -> Gather Workers Planned: 10 -> Append -> Parallel Seq Scan on p1_c1 -> Parallel Seq Scan on p1_c1_c1 -> Parallel Seq Scan on p1_c1_c2 -> Hash -> Gather Workers Planned: 1 -> Append -> Parallel Seq Scan on p2_c1 -> Parallel Seq Scan on p2_c1_c1 -> Parallel Seq Scan on p2_c1_c2 (15 rows) /*+Parallel(p2_c1 10 hard)*/ EXPLAIN (COSTS false) SELECT * FROM p1_c1 join p2_c1 on p1_c1.id = p2_c1.id; LOG: pg_hint_plan: used hint: Parallel(p2_c1 10 hard) not used hint: duplication hint: error hint: QUERY PLAN ------------------------------------------------------- Hash Join Hash Cond: (p1_c1.id = p2_c1.id) -> Gather Workers Planned: 1 -> Append -> Parallel Seq Scan on p1_c1 -> Parallel Seq Scan on p1_c1_c1 -> Parallel Seq Scan on p1_c1_c2 -> Hash -> Gather Workers Planned: 10 -> Append -> Parallel Seq Scan on p2_c1 -> Parallel Seq Scan on p2_c1_c1 -> Parallel Seq Scan on p2_c1_c2 (15 rows) /*+Parallel(p1_c1 10 hard) Parallel(p2_c1 10 hard)*/ EXPLAIN (COSTS false) SELECT * FROM p1_c1 join p2_c1 on p1_c1.id = p2_c1.id; LOG: pg_hint_plan: used hint: Parallel(p1_c1 10 hard) Parallel(p2_c1 10 hard) not used hint: duplication hint: error hint: QUERY PLAN ------------------------------------------------------- Hash Join Hash Cond: (p1_c1.id = p2_c1.id) -> Gather Workers Planned: 10 -> Append -> Parallel Seq Scan on p1_c1 -> Parallel Seq Scan on p1_c1_c1 -> Parallel Seq Scan on p1_c1_c2 -> Hash -> Gather Workers Planned: 10 -> Append -> Parallel Seq Scan on p2_c1 -> Parallel Seq Scan on p2_c1_c1 -> Parallel Seq Scan on p2_c1_c2 (15 rows) -- Joins on inheritance tables SET parallel_setup_cost to 0; SET parallel_tuple_cost to 0; SET min_parallel_relation_size to 0; /*+Parallel(p1 10)*/ EXPLAIN (COSTS false) SELECT * FROM p1 join p2 on p1.id = p2.id; LOG: pg_hint_plan: used hint: Parallel(p1 10 soft) not used hint: duplication hint: error hint: QUERY PLAN ------------------------------------------------------- Hash Join Hash Cond: (p1.id = p2.id) -> Gather Workers Planned: 1 -> Append -> Parallel Seq Scan on p1 -> Parallel Seq Scan on p1_c1 -> Parallel Seq Scan on p1_c2 -> Parallel Seq Scan on p1_c3 -> Parallel Seq Scan on p1_c4 -> Parallel Seq Scan on p1_c1_c1 -> Parallel Seq Scan on p1_c1_c2 -> Parallel Seq Scan on p1_c3_c1 -> Parallel Seq Scan on p1_c3_c2 -> Hash -> Gather Workers Planned: 1 -> Append -> Parallel Seq Scan on p2 -> Parallel Seq Scan on p2_c1 -> Parallel Seq Scan on p2_c2 -> Parallel Seq Scan on p2_c3 -> Parallel Seq Scan on p2_c4 -> Parallel Seq Scan on p2_c1_c1 -> Parallel Seq Scan on p2_c1_c2 -> Parallel Seq Scan on p2_c3_c1 -> Parallel Seq Scan on p2_c3_c2 (27 rows) SET parallel_setup_cost to DEFAULT; SET parallel_tuple_cost to DEFAULT; SET min_parallel_relation_size to DEFAULT; /*+Parallel(p2 10 hard)*/ EXPLAIN (COSTS false) SELECT * FROM p1 join p2 on p1.id = p2.id; LOG: pg_hint_plan: used hint: Parallel(p2 10 hard) not used hint: duplication hint: error hint: QUERY PLAN ------------------------------------------------------- Hash Join Hash Cond: (p1.id = p2.id) -> Gather Workers Planned: 1 -> Append -> Parallel Seq Scan on p1 -> Parallel Seq Scan on p1_c1 -> Parallel Seq Scan on p1_c2 -> Parallel Seq Scan on p1_c3 -> Parallel Seq Scan on p1_c4 -> Parallel Seq Scan on p1_c1_c1 -> Parallel Seq Scan on p1_c1_c2 -> Parallel Seq Scan on p1_c3_c1 -> Parallel Seq Scan on p1_c3_c2 -> Hash -> Gather Workers Planned: 10 -> Append -> Parallel Seq Scan on p2 -> Parallel Seq Scan on p2_c1 -> Parallel Seq Scan on p2_c2 -> Parallel Seq Scan on p2_c3 -> Parallel Seq Scan on p2_c4 -> Parallel Seq Scan on p2_c1_c1 -> Parallel Seq Scan on p2_c1_c2 -> Parallel Seq Scan on p2_c3_c1 -> Parallel Seq Scan on p2_c3_c2 (27 rows) /*+Parallel(p2 10 hard) Parallel(p1 5 hard) */ EXPLAIN (COSTS false) SELECT * FROM p1 join p2 on p1.id = p2.id; LOG: pg_hint_plan: used hint: Parallel(p1 5 hard) Parallel(p2 10 hard) not used hint: duplication hint: error hint: QUERY PLAN ------------------------------------------------------- Hash Join Hash Cond: (p1.id = p2.id) -> Gather Workers Planned: 5 -> Append -> Parallel Seq Scan on p1 -> Parallel Seq Scan on p1_c1 -> Parallel Seq Scan on p1_c2 -> Parallel Seq Scan on p1_c3 -> Parallel Seq Scan on p1_c4 -> Parallel Seq Scan on p1_c1_c1 -> Parallel Seq Scan on p1_c1_c2 -> Parallel Seq Scan on p1_c3_c1 -> Parallel Seq Scan on p1_c3_c2 -> Hash -> Gather Workers Planned: 10 -> Append -> Parallel Seq Scan on p2 -> Parallel Seq Scan on p2_c1 -> Parallel Seq Scan on p2_c2 -> Parallel Seq Scan on p2_c3 -> Parallel Seq Scan on p2_c4 -> Parallel Seq Scan on p2_c1_c1 -> Parallel Seq Scan on p2_c1_c2 -> Parallel Seq Scan on p2_c3_c1 -> Parallel Seq Scan on p2_c3_c2 (27 rows) -- Mixture with a scan hint -- p1 can be parallel /*+Parallel(p1 10 hard) IndexScan(p2) */ EXPLAIN (COSTS false) SELECT * FROM p1 join p2 on p1.id = p2.id; LOG: pg_hint_plan: used hint: IndexScan(p2) Parallel(p1 10 hard) not used hint: duplication hint: error hint: QUERY PLAN ------------------------------------------------------- Hash Join Hash Cond: (p1.id = p2.id) -> Gather Workers Planned: 10 -> Append -> Parallel Seq Scan on p1 -> Parallel Seq Scan on p1_c1 -> Parallel Seq Scan on p1_c2 -> Parallel Seq Scan on p1_c3 -> Parallel Seq Scan on p1_c4 -> Parallel Seq Scan on p1_c1_c1 -> Parallel Seq Scan on p1_c1_c2 -> Parallel Seq Scan on p1_c3_c1 -> Parallel Seq Scan on p1_c3_c2 -> Hash -> Gather Workers Planned: 1 -> Append -> Parallel Seq Scan on p2 -> Parallel Seq Scan on p2_c1 -> Parallel Seq Scan on p2_c2 -> Parallel Seq Scan on p2_c3 -> Parallel Seq Scan on p2_c4 -> Parallel Seq Scan on p2_c1_c1 -> Parallel Seq Scan on p2_c1_c2 -> Parallel Seq Scan on p2_c3_c1 -> Parallel Seq Scan on p2_c3_c2 (27 rows) -- seqscan doesn't harm parallelism /*+Parallel(p1 10 hard) SeqScan(p1) */ EXPLAIN (COSTS false) SELECT * FROM p1 join p2 on p1.id = p2.id; LOG: pg_hint_plan: used hint: SeqScan(p1) Parallel(p1 10 hard) not used hint: duplication hint: error hint: QUERY PLAN ------------------------------------------------------- Hash Join Hash Cond: (p1.id = p2.id) -> Gather Workers Planned: 10 -> Append -> Parallel Seq Scan on p1 -> Parallel Seq Scan on p1_c1 -> Parallel Seq Scan on p1_c2 -> Parallel Seq Scan on p1_c3 -> Parallel Seq Scan on p1_c4 -> Parallel Seq Scan on p1_c1_c1 -> Parallel Seq Scan on p1_c1_c2 -> Parallel Seq Scan on p1_c3_c1 -> Parallel Seq Scan on p1_c3_c2 -> Hash -> Gather Workers Planned: 1 -> Append -> Parallel Seq Scan on p2 -> Parallel Seq Scan on p2_c1 -> Parallel Seq Scan on p2_c2 -> Parallel Seq Scan on p2_c3 -> Parallel Seq Scan on p2_c4 -> Parallel Seq Scan on p2_c1_c1 -> Parallel Seq Scan on p2_c1_c2 -> Parallel Seq Scan on p2_c3_c1 -> Parallel Seq Scan on p2_c3_c2 (27 rows) -- parallelism is not available for the case /*+Parallel(p1 10 hard) IndexScan(p1) */ EXPLAIN (COSTS false) SELECT * FROM p1 join p2 on p1.id = p2.id; LOG: pg_hint_plan: used hint: IndexScan(p1) Parallel(p1 10 hard) not used hint: duplication hint: error hint: QUERY PLAN ------------------------------------------------------- Hash Join Hash Cond: (p1.id = p2.id) -> Gather Workers Planned: 10 -> Append -> Parallel Seq Scan on p1 -> Parallel Seq Scan on p1_c1 -> Parallel Seq Scan on p1_c2 -> Parallel Seq Scan on p1_c3 -> Parallel Seq Scan on p1_c4 -> Parallel Seq Scan on p1_c1_c1 -> Parallel Seq Scan on p1_c1_c2 -> Parallel Seq Scan on p1_c3_c1 -> Parallel Seq Scan on p1_c3_c2 -> Hash -> Gather Workers Planned: 1 -> Append -> Parallel Seq Scan on p2 -> Parallel Seq Scan on p2_c1 -> Parallel Seq Scan on p2_c2 -> Parallel Seq Scan on p2_c3 -> Parallel Seq Scan on p2_c4 -> Parallel Seq Scan on p2_c1_c1 -> Parallel Seq Scan on p2_c1_c2 -> Parallel Seq Scan on p2_c3_c1 -> Parallel Seq Scan on p2_c3_c2 (27 rows) -- Parallel on UNION EXPLAIN (COSTS false) SELECT id FROM p1 UNION ALL SELECT id FROM p2; QUERY PLAN ---------------------------- Append -> Seq Scan on p1 -> Seq Scan on p1_c1 -> Seq Scan on p1_c2 -> Seq Scan on p1_c3 -> Seq Scan on p1_c4 -> Seq Scan on p1_c1_c1 -> Seq Scan on p1_c1_c2 -> Seq Scan on p1_c3_c1 -> Seq Scan on p1_c3_c2 -> Seq Scan on p2 -> Seq Scan on p2_c1 -> Seq Scan on p2_c2 -> Seq Scan on p2_c3 -> Seq Scan on p2_c4 -> Seq Scan on p2_c1_c1 -> Seq Scan on p2_c1_c2 -> Seq Scan on p2_c3_c1 -> Seq Scan on p2_c3_c2 (19 rows) -- some of the scans are not parallel, so this cannot be parallel SET parallel_setup_cost to 0; SET parallel_tuple_cost to 0; SET min_parallel_relation_size to 0; SET max_parallel_workers_per_gather to 0; /*+Parallel(p1 10) */ EXPLAIN (COSTS false) SELECT id FROM p1 UNION ALL SELECT id FROM p2; LOG: pg_hint_plan: used hint: Parallel(p1 10 soft) not used hint: duplication hint: error hint: QUERY PLAN ------------------------------------------- Gather Workers Planned: 1 -> Append -> Parallel Seq Scan on p1 -> Parallel Seq Scan on p1_c1 -> Parallel Seq Scan on p1_c2 -> Parallel Seq Scan on p1_c3 -> Parallel Seq Scan on p1_c4 -> Parallel Seq Scan on p1_c1_c1 -> Parallel Seq Scan on p1_c1_c2 -> Parallel Seq Scan on p1_c3_c1 -> Parallel Seq Scan on p1_c3_c2 -> Parallel Seq Scan on p2 -> Parallel Seq Scan on p2_c1 -> Parallel Seq Scan on p2_c2 -> Parallel Seq Scan on p2_c3 -> Parallel Seq Scan on p2_c4 -> Parallel Seq Scan on p2_c1_c1 -> Parallel Seq Scan on p2_c1_c2 -> Parallel Seq Scan on p2_c3_c1 -> Parallel Seq Scan on p2_c3_c2 (21 rows) -- all children are parallel, so this can be parallel /*+Parallel(p1 10) Parallel(p2 10) */ EXPLAIN (COSTS false) SELECT id FROM p1 UNION ALL SELECT id FROM p2; LOG: pg_hint_plan: used hint: Parallel(p1 10 soft) Parallel(p2 10 soft) not used hint: duplication hint: error hint: QUERY PLAN ------------------------------------------- Gather Workers Planned: 1 -> Append -> Parallel Seq Scan on p1 -> Parallel Seq Scan on p1_c1 -> Parallel Seq Scan on p1_c2 -> Parallel Seq Scan on p1_c3 -> Parallel Seq Scan on p1_c4 -> Parallel Seq Scan on p1_c1_c1 -> Parallel Seq Scan on p1_c1_c2 -> Parallel Seq Scan on p1_c3_c1 -> Parallel Seq Scan on p1_c3_c2 -> Parallel Seq Scan on p2 -> Parallel Seq Scan on p2_c1 -> Parallel Seq Scan on p2_c2 -> Parallel Seq Scan on p2_c3 -> Parallel Seq Scan on p2_c4 -> Parallel Seq Scan on p2_c1_c1 -> Parallel Seq Scan on p2_c1_c2 -> Parallel Seq Scan on p2_c3_c1 -> Parallel Seq Scan on p2_c3_c2 (21 rows) SET parallel_setup_cost to DEFAULT; SET parallel_tuple_cost to DEFAULT; SET min_parallel_relation_size to DEFAULT; SET max_parallel_workers_per_gather to DEFAULT; /*+Parallel(p1 10 hard)Parallel(p2 10 hard) */ EXPLAIN (COSTS false) SELECT id FROM p1 UNION ALL SELECT id FROM p2; LOG: pg_hint_plan: used hint: Parallel(p1 10 hard) Parallel(p2 10 hard) not used hint: duplication hint: error hint: QUERY PLAN ------------------------------------------- Gather Workers Planned: 10 -> Append -> Parallel Seq Scan on p1 -> Parallel Seq Scan on p1_c1 -> Parallel Seq Scan on p1_c2 -> Parallel Seq Scan on p1_c3 -> Parallel Seq Scan on p1_c4 -> Parallel Seq Scan on p1_c1_c1 -> Parallel Seq Scan on p1_c1_c2 -> Parallel Seq Scan on p1_c3_c1 -> Parallel Seq Scan on p1_c3_c2 -> Parallel Seq Scan on p2 -> Parallel Seq Scan on p2_c1 -> Parallel Seq Scan on p2_c2 -> Parallel Seq Scan on p2_c3 -> Parallel Seq Scan on p2_c4 -> Parallel Seq Scan on p2_c1_c1 -> Parallel Seq Scan on p2_c1_c2 -> Parallel Seq Scan on p2_c3_c1 -> Parallel Seq Scan on p2_c3_c2 (21 rows) -- num of workers of non-hinted relations should be default value SET parallel_setup_cost to 0; SET parallel_tuple_cost to 0; SET min_parallel_relation_size to 0; SET max_parallel_workers_per_gather to 3; /*+Parallel(p1 10 hard) */ EXPLAIN (COSTS false) SELECT * FROM p1 join t1 on p1.id = t1.id; LOG: pg_hint_plan: used hint: Parallel(p1 10 hard) not used hint: duplication hint: error hint: QUERY PLAN ------------------------------------------------------- Hash Join Hash Cond: (t1.id = p1.id) -> Gather Workers Planned: 3 -> Parallel Seq Scan on t1 -> Hash -> Gather Workers Planned: 10 -> Append -> Parallel Seq Scan on p1 -> Parallel Seq Scan on p1_c1 -> Parallel Seq Scan on p1_c2 -> Parallel Seq Scan on p1_c3 -> Parallel Seq Scan on p1_c4 -> Parallel Seq Scan on p1_c1_c1 -> Parallel Seq Scan on p1_c1_c2 -> Parallel Seq Scan on p1_c3_c1 -> Parallel Seq Scan on p1_c3_c2 (18 rows) -- Negative hint SET parallel_setup_cost to 0; SET parallel_tuple_cost to 0; SET min_parallel_relation_size to 0; SET max_parallel_workers_per_gather to 5; EXPLAIN (COSTS false) SELECT * FROM p1; QUERY PLAN ------------------------------------------- Gather Workers Planned: 1 -> Append -> Parallel Seq Scan on p1 -> Parallel Seq Scan on p1_c1 -> Parallel Seq Scan on p1_c2 -> Parallel Seq Scan on p1_c3 -> Parallel Seq Scan on p1_c4 -> Parallel Seq Scan on p1_c1_c1 -> Parallel Seq Scan on p1_c1_c2 -> Parallel Seq Scan on p1_c3_c1 -> Parallel Seq Scan on p1_c3_c2 (12 rows) /*+Parallel(p1 0 hard)*/ EXPLAIN (COSTS false) SELECT * FROM p1; LOG: pg_hint_plan: used hint: Parallel(p1 0 hard) not used hint: duplication hint: error hint: QUERY PLAN ---------------------------- Append -> Seq Scan on p1 -> Seq Scan on p1_c1 -> Seq Scan on p1_c2 -> Seq Scan on p1_c3 -> Seq Scan on p1_c4 -> Seq Scan on p1_c1_c1 -> Seq Scan on p1_c1_c2 -> Seq Scan on p1_c3_c1 -> Seq Scan on p1_c3_c2 (10 rows) -- Errors /*+Parallel(p1 100x hard)Parallel(p1 -1000 hard)Parallel(p1 1000000 hard) Parallel(p1 10 hoge)Parallel(p1)Parallel(p1 100 soft x)*/ EXPLAIN (COSTS false) SELECT id FROM p1 UNION ALL SELECT id FROM p2; INFO: pg_hint_plan: hint syntax error at or near "100x" DETAIL: number of workers must be a number: Parallel INFO: pg_hint_plan: hint syntax error at or near "-1000" DETAIL: number of workers must be positive: Parallel INFO: pg_hint_plan: hint syntax error at or near "1000000" DETAIL: number of workers = 1000000 is larger than max_worker_processes(100): Parallel INFO: pg_hint_plan: hint syntax error at or near "hoge" DETAIL: enforcement must be soft or hard: Parallel INFO: pg_hint_plan: hint syntax error at or near ")" DETAIL: wrong number of arguments (1): Parallel INFO: pg_hint_plan: hint syntax error at or near ")" DETAIL: wrong number of arguments (4): Parallel LOG: pg_hint_plan: used hint: not used hint: duplication hint: error hint: Parallel(p1 100x hard) Parallel(p1 -1000 hard) Parallel(p1 1000000 hard) Parallel(p1 10 hard) Parallel() Parallel() QUERY PLAN ------------------------------------------- Gather Workers Planned: 1 -> Append -> Parallel Seq Scan on p1 -> Parallel Seq Scan on p1_c1 -> Parallel Seq Scan on p1_c2 -> Parallel Seq Scan on p1_c3 -> Parallel Seq Scan on p1_c4 -> Parallel Seq Scan on p1_c1_c1 -> Parallel Seq Scan on p1_c1_c2 -> Parallel Seq Scan on p1_c3_c1 -> Parallel Seq Scan on p1_c3_c2 -> Parallel Seq Scan on p2 -> Parallel Seq Scan on p2_c1 -> Parallel Seq Scan on p2_c2 -> Parallel Seq Scan on p2_c3 -> Parallel Seq Scan on p2_c4 -> Parallel Seq Scan on p2_c1_c1 -> Parallel Seq Scan on p2_c1_c2 -> Parallel Seq Scan on p2_c3_c1 -> Parallel Seq Scan on p2_c3_c2 (21 rows) ALTER SYSTEM SET session_preload_libraries TO DEFAULT; SELECT pg_reload_conf(); pg_reload_conf ---------------- t (1 row)