SET pg_hint_plan.enable_hint TO on;
SET pg_hint_plan.debug_print TO on;
SET client_min_messages TO LOG;
-SET search_path TO public;
-SET max_parallel_workers_per_gather TO 0;
-SET enable_indexscan to false;
-SET enable_bitmapscan to false;
-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;
CREATE TABLE s1.tl (a int);
INSERT INTO s1.tl (SELECT a FROM generate_series(0, 100000) a);
+-- Queries on ordinary tables with default setting
EXPLAIN (COSTS false) SELECT * FROM s1.t1;
QUERY PLAN
----------------
Seq Scan on t1
(1 row)
-/*+Parallel(t1 10)*/
+SET parallel_setup_cost to 0;
+SET parallel_tuple_cost to 0;
+SET min_parallel_table_scan_size to 0;
+SET min_parallel_index_scan_size to 0;
+SET max_parallel_workers_per_gather to DEFAULT;
+/*+Parallel(t1 8)*/
EXPLAIN (COSTS false) SELECT * FROM s1.t1;
LOG: pg_hint_plan:
used hint:
-Parallel(t1 10 soft)
+Parallel(t1 8 soft)
not used hint:
duplication hint:
error hint:
-> Parallel Seq Scan on t1
(3 rows)
-/*+Parallel(t1 10 soft)*/
+/*+Parallel(t1 8 soft)*/
EXPLAIN (COSTS false) SELECT * FROM s1.t1;
LOG: pg_hint_plan:
used hint:
-Parallel(t1 10 soft)
+Parallel(t1 8 soft)
not used hint:
duplication hint:
error hint:
-> Parallel Seq Scan on t1
(3 rows)
-/*+Parallel(t1 10 hard)*/
+/*+Parallel(t1 8 hard)*/
EXPLAIN (COSTS false) SELECT * FROM s1.t1;
LOG: pg_hint_plan:
used hint:
-Parallel(t1 10 hard)
+Parallel(t1 8 hard)
not used hint:
duplication hint:
error hint:
QUERY PLAN
-------------------------------
Gather
- Workers Planned: 10
+ Workers Planned: 8
-> Parallel Seq Scan on t1
(3 rows)
--- Inheritnce tables
-/*+Parallel(p1 10 soft)*/
+-- Queries on inheritance tables
+SET parallel_setup_cost to 0;
+SET parallel_tuple_cost to 0;
+SET min_parallel_table_scan_size to 0;
+SET min_parallel_index_scan_size to 0;
+/*+Parallel(p1 8)*/
EXPLAIN (COSTS false) SELECT * FROM p1;
LOG: pg_hint_plan:
used hint:
-Parallel(p1 10 soft)
+Parallel(p1 8 soft)
not used hint:
duplication hint:
error hint:
-> Parallel Seq Scan on p1_c3_c2
(12 rows)
-/*+Parallel(p1 10 hard)*/
+SET parallel_setup_cost to DEFAULT;
+SET parallel_tuple_cost to DEFAULT;
+SET min_parallel_table_scan_size to DEFAULT;
+SET min_parallel_index_scan_size to DEFAULT;
+/*+Parallel(p1 8 hard)*/
EXPLAIN (COSTS false) SELECT * FROM p1;
LOG: pg_hint_plan:
used hint:
-Parallel(p1 10 hard)
+Parallel(p1 8 hard)
not used hint:
duplication hint:
error hint:
QUERY PLAN
-------------------------------------------
Gather
- Workers Planned: 10
+ Workers Planned: 8
+ -> 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 makes the whole inheritance parallel
+/*+Parallel(p1_c1 8 hard)*/
+EXPLAIN (COSTS false) SELECT * FROM p1;
+LOG: pg_hint_plan:
+used hint:
+Parallel(p1_c1 8 hard)
+not used hint:
+duplication hint:
+error hint:
+
+ QUERY PLAN
+-------------------------------------------
+ Gather
+ Workers Planned: 8
-> Append
-> Parallel Seq Scan on p1
-> Parallel Seq Scan on p1_c1
(12 rows)
-- Joins
-EXPLAIN (COSTS false) SELECT * FROM p1_c1 join p2_c1 on p1_c1.id = p2_c1.id;
- QUERY PLAN
-----------------------------------------
+EXPLAIN (COSTS false) SELECT * FROM p1_c1_c1 join p2_c1_c1 on p1_c1_c1.id = p2_c1_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 Cond: (p1_c1_c1.id = p2_c1_c1.id)
+ -> Seq Scan on p1_c1_c1
-> Hash
- -> Append
- -> Seq Scan on p2_c1
- -> Seq Scan on p2_c1_c1
- -> Seq Scan on p2_c1_c2
-(11 rows)
+ -> Seq Scan on p2_c1_c1
+(5 rows)
-/*+Parallel(p1_c1 10 hard)*/
-EXPLAIN (COSTS false) SELECT * FROM p1_c1 join p2_c1 on p1_c1.id = p2_c1.id;
+/*+Parallel(p1_c1_c1 8 hard)*/
+EXPLAIN (COSTS false) SELECT * FROM p1_c1_c1 join p2_c1_c1 on p1_c1_c1.id = p2_c1_c1.id;
LOG: pg_hint_plan:
used hint:
-Parallel(p1_c1 10 hard)
+Parallel(p1_c1_c1 8 hard)
not used hint:
duplication hint:
error hint:
QUERY PLAN
-------------------------------------------------
+ Hash Join
+ Hash Cond: (p2_c1_c1.id = p1_c1_c1.id)
+ -> Seq Scan on p2_c1_c1
+ -> Hash
+ -> Gather
+ Workers Planned: 8
+ -> Parallel Seq Scan on p1_c1_c1
+(7 rows)
+
+SET parallel_setup_cost to 0;
+SET parallel_tuple_cost to 0;
+SET min_parallel_table_scan_size to 0;
+SET min_parallel_index_scan_size to 0;
+/*+Parallel(p1_c1_c1 8 soft) Parallel(p2_c1_c1 0)*/
+EXPLAIN (COSTS false) SELECT * FROM p1_c1_c1 join p2_c1_c1 on p1_c1_c1.id = p2_c1_c1.id;
+LOG: pg_hint_plan:
+used hint:
+Parallel(p1_c1_c1 8 soft)
+Parallel(p2_c1_c1 0 soft)
+not used hint:
+duplication hint:
+error hint:
+
+ QUERY PLAN
+------------------------------------------------
Gather
- Workers Planned: 10
+ Workers Planned: 1
-> Hash Join
- Hash Cond: (p1_c1.id = p2_c1.id)
- -> Append
- -> Parallel Seq Scan on p1_c1
- -> Parallel Seq Scan on p1_c1_c1
- -> Parallel Seq Scan on p1_c1_c2
+ Hash Cond: (p1_c1_c1.id = p2_c1_c1.id)
+ -> Parallel Seq Scan on p1_c1_c1
-> Hash
- -> Append
- -> Seq Scan on p2_c1
- -> Seq Scan on p2_c1_c1
- -> Seq Scan on p2_c1_c2
-(13 rows)
+ -> Seq Scan on p2_c1_c1
+(7 rows)
-/*+Parallel(p2_c1 10 hard)*/
-EXPLAIN (COSTS false) SELECT * FROM p1_c1 join p2_c1 on p1_c1.id = p2_c1.id;
+/*+Parallel(p1_c1_c1 8 hard) Parallel(p2_c1_c1 0)*/
+EXPLAIN (COSTS false) SELECT * FROM p1_c1_c1 join p2_c1_c1 on p1_c1_c1.id = p2_c1_c1.id;
LOG: pg_hint_plan:
used hint:
-Parallel(p2_c1 10 hard)
+Parallel(p1_c1_c1 8 hard)
+Parallel(p2_c1_c1 0 soft)
not used hint:
duplication hint:
error hint:
- QUERY PLAN
--------------------------------------------------
+ QUERY PLAN
+------------------------------------------------
Gather
- Workers Planned: 10
+ Workers Planned: 8
-> Hash Join
- Hash Cond: (p2_c1.id = p1_c1.id)
- -> Append
- -> Parallel Seq Scan on p2_c1
- -> Parallel Seq Scan on p2_c1_c1
- -> Parallel Seq Scan on p2_c1_c2
+ Hash Cond: (p1_c1_c1.id = p2_c1_c1.id)
+ -> Parallel Seq Scan on p1_c1_c1
-> Hash
- -> Append
- -> Seq Scan on p1_c1
- -> Seq Scan on p1_c1_c1
- -> Seq Scan on p1_c1_c2
-(13 rows)
+ -> Seq Scan on p2_c1_c1
+(7 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;
+/*+Parallel(p1_c1_c1 8 hard) Parallel(p2_c1_c1 8 hard)*/
+EXPLAIN (COSTS false) SELECT * FROM p1_c1_c1 join p2_c1_c1 on p1_c1_c1.id = p2_c1_c1.id;
LOG: pg_hint_plan:
used hint:
-Parallel(p1_c1 10 hard)
-Parallel(p2_c1 10 hard)
+Parallel(p1_c1_c1 8 hard)
+Parallel(p2_c1_c1 8 hard)
not used hint:
duplication hint:
error hint:
- QUERY PLAN
--------------------------------------------------------
+ QUERY PLAN
+-------------------------------------------------
Hash Join
- Hash Cond: (p1_c1.id = p2_c1.id)
+ Hash Cond: (p1_c1_c1.id = p2_c1_c1.id)
-> Gather
- Workers Planned: 10
+ Workers Planned: 8
+ -> Parallel Seq Scan on p1_c1_c1
+ -> Hash
+ -> Gather
+ Workers Planned: 8
+ -> Parallel Seq Scan on p2_c1_c1
+(9 rows)
+
+-- Joins on inheritance tables
+SET parallel_setup_cost to 0;
+SET parallel_tuple_cost to 0;
+SET min_parallel_table_scan_size to 0;
+SET min_parallel_index_scan_size to 0;
+/*+Parallel(p1 8)*/
+EXPLAIN (COSTS false) SELECT * FROM p1 join p2 on p1.id = p2.id;
+LOG: pg_hint_plan:
+used hint:
+Parallel(p1 8 soft)
+not used hint:
+duplication hint:
+error hint:
+
+ QUERY PLAN
+-------------------------------------------------
+ Gather
+ Workers Planned: 1
+ -> Hash Join
+ Hash Cond: (p1.id = p2.id)
-> 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
- -> Hash
- -> Gather
- Workers Planned: 10
+ -> Parallel Seq Scan on p1_c3_c1
+ -> Parallel Seq Scan on p1_c3_c2
+ -> Hash
-> Append
- -> Parallel Seq Scan on p2_c1
- -> Parallel Seq Scan on p2_c1_c1
- -> Parallel Seq Scan on p2_c1_c2
-(15 rows)
+ -> 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
+(25 rows)
--- Joins on inheritance tables
-/*+Parallel(p1 10)*/
+/*+Parallel(p1 8)Parallel(p2 0)*/
EXPLAIN (COSTS false) SELECT * FROM p1 join p2 on p1.id = p2.id;
LOG: pg_hint_plan:
used hint:
-Parallel(p1 10 soft)
+Parallel(p1 8 soft)
+Parallel(p2 0 soft)
not used hint:
duplication hint:
error hint:
-> Seq Scan on p2_c3_c2
(25 rows)
-/*+Parallel(p2 10 hard)*/
+SET parallel_setup_cost to DEFAULT;
+SET parallel_tuple_cost to DEFAULT;
+SET min_parallel_table_scan_size to DEFAULT;
+SET min_parallel_index_scan_size to DEFAULT;
+/*+Parallel(p2 8 soft)*/
+EXPLAIN (COSTS false) SELECT * FROM p1 join p2 on p1.id = p2.id;
+LOG: pg_hint_plan:
+used hint:
+Parallel(p2 8 soft)
+not used hint:
+duplication hint:
+error hint:
+
+ QUERY PLAN
+-------------------------------------------------
+ Gather
+ Workers Planned: 1
+ -> Hash Join
+ Hash Cond: (p2.id = p1.id)
+ -> 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
+ -> Hash
+ -> 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
+(25 rows)
+
+/*+Parallel(p2 8 hard)*/
EXPLAIN (COSTS false) SELECT * FROM p1 join p2 on p1.id = p2.id;
LOG: pg_hint_plan:
used hint:
-Parallel(p2 10 hard)
+Parallel(p2 8 hard)
not used hint:
duplication hint:
error hint:
QUERY PLAN
-------------------------------------------------
Gather
- Workers Planned: 10
+ Workers Planned: 8
-> Hash Join
Hash Cond: (p2.id = p1.id)
-> Append
-> Seq Scan on p1_c3_c2
(25 rows)
-/*+Parallel(p2 10 hard) Parallel(p1 5 hard) */
+/*+Parallel(p2 8 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)
+Parallel(p2 8 hard)
not used hint:
duplication hint:
error hint:
-> Parallel Seq Scan on p1_c3_c2
-> Hash
-> Gather
- Workers Planned: 10
+ Workers Planned: 8
-> Append
-> Parallel Seq Scan on p2
-> Parallel Seq Scan on p2_c1
-> Parallel Seq Scan on p2_c3_c2
(27 rows)
+-- Mixture with a scan hint
+-- p1 can be parallel
+/*+Parallel(p1 8 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 8 hard)
+not used hint:
+duplication hint:
+error hint:
+
+ QUERY PLAN
+--------------------------------------------------------------
+ Hash Join
+ Hash Cond: (p2.id = p1.id)
+ -> Append
+ -> Index Scan using p2_id2_val on p2
+ -> Index Scan using p2_c1_id2_val on p2_c1
+ -> Index Scan using p2_c2_id2_val on p2_c2
+ -> Index Scan using p2_c3_id_val_idx on p2_c3
+ -> Index Scan using p2_c4_id_val_idx on p2_c4
+ -> Index Scan using p2_c1_c1_id_val_idx on p2_c1_c1
+ -> Index Scan using p2_c1_c2_id_val_idx on p2_c1_c2
+ -> Index Scan using p2_c3_c1_id_val_idx on p2_c3_c1
+ -> Index Scan using p2_c3_c2_id_val_idx on p2_c3_c2
+ -> Hash
+ -> Gather
+ Workers Planned: 8
+ -> 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
+(25 rows)
+
+-- Parallel sequential scan
+/*+Parallel(p1 8 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 8 hard)
+not used hint:
+duplication hint:
+error hint:
+
+ QUERY PLAN
+-------------------------------------------------
+ Gather
+ Workers Planned: 8
+ -> Hash Join
+ Hash Cond: (p1.id = p2.id)
+ -> 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
+ -> Append
+ -> 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
+(25 rows)
+
+-- Parallel index scan
+/*+Parallel(p1 8 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 8 hard)
+not used hint:
+duplication hint:
+error hint:
+
+ QUERY PLAN
+-----------------------------------------------------------------------
+ Gather
+ Workers Planned: 8
+ -> Hash Join
+ Hash Cond: (p1.id = p2.id)
+ -> Append
+ -> Parallel Index Scan using p1_pkey on p1
+ -> Parallel Index Scan using p1_c1_pkey on p1_c1
+ -> Parallel Index Scan using p1_c2_pkey on p1_c2
+ -> Parallel Index Scan using p1_c3_pkey on p1_c3
+ -> Parallel Index Scan using p1_c4_pkey on p1_c4
+ -> Parallel Index Scan using p1_c1_c1_pkey on p1_c1_c1
+ -> Parallel Index Scan using p1_c1_c2_pkey on p1_c1_c2
+ -> Parallel Index Scan using p1_c3_c1_pkey on p1_c3_c1
+ -> Parallel Index Scan using p1_c3_c2_pkey on p1_c3_c2
+ -> Hash
+ -> Append
+ -> 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
+(25 rows)
+
+-- This hint doesn't turn on parallel, so the Parallel hint is ignored
+set max_parallel_workers_per_gather TO 0;
+/*+Parallel(p1 0 hard) IndexScan(p1) */
+EXPLAIN (COSTS false) SELECT * FROM p1 join p2 on p1.id = p2.id;
+LOG: pg_hint_plan:
+used hint:
+IndexScan(p1)
+not used hint:
+Parallel(p1 0 hard)
+duplication hint:
+error hint:
+
+ QUERY PLAN
+--------------------------------------------------------
+ Hash Join
+ Hash Cond: (p1.id = p2.id)
+ -> Append
+ -> Index Scan using p1_pkey on p1
+ -> Index Scan using p1_c1_pkey on p1_c1
+ -> Index Scan using p1_c2_pkey on p1_c2
+ -> Index Scan using p1_c3_pkey on p1_c3
+ -> Index Scan using p1_c4_pkey on p1_c4
+ -> Index Scan using p1_c1_c1_pkey on p1_c1_c1
+ -> Index Scan using p1_c1_c2_pkey on p1_c1_c2
+ -> Index Scan using p1_c3_c1_pkey on p1_c3_c1
+ -> Index Scan using p1_c3_c2_pkey on p1_c3_c2
+ -> Hash
+ -> Append
+ -> 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
+(23 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)
+
+-- parallel hinting on any relation enables parallel
+SET parallel_setup_cost to 0;
+SET parallel_tuple_cost to 0;
+SET min_parallel_table_scan_size to 0;
+SET min_parallel_index_scan_size to 0;
+SET max_parallel_workers_per_gather to 0;
+/*+Parallel(p1 8) */
+EXPLAIN (COSTS false) SELECT id FROM p1 UNION ALL SELECT id FROM p2;
+LOG: pg_hint_plan:
+used hint:
+Parallel(p1 8 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 hint does the same thing
+/*+Set(max_parallel_workers_per_gather 1)*/
+EXPLAIN (COSTS false) SELECT id FROM p1 UNION ALL SELECT id FROM p2;
+LOG: pg_hint_plan:
+used hint:
+Set(max_parallel_workers_per_gather 1)
+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)
+
+-- applies largest number of workers on merged parallel paths
+SET parallel_setup_cost to DEFAULT;
+SET parallel_tuple_cost to DEFAULT;
+SET min_parallel_table_scan_size to DEFAULT;
+SET min_parallel_index_scan_size to DEFAULT;
+SET max_parallel_workers_per_gather to 8;
+/*+Parallel(p1 5 hard)Parallel(p2 6 hard) */
+EXPLAIN (COSTS false) SELECT id FROM p1 UNION ALL SELECT id FROM p2;
+LOG: pg_hint_plan:
+used hint:
+Parallel(p1 5 hard)
+Parallel(p2 6 hard)
+not used hint:
+duplication hint:
+error hint:
+
+ QUERY PLAN
+-------------------------------------------
+ Gather
+ Workers Planned: 6
+ -> 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_table_scan_size to 0;
+SET min_parallel_index_scan_size to 0;
+SET max_parallel_workers_per_gather to 3;
+SET enable_indexscan to false;
+/*+Parallel(p1 8 hard) */
+EXPLAIN (COSTS false) SELECT * FROM p1 join t1 on p1.id = t1.id;
+LOG: pg_hint_plan:
+used hint:
+Parallel(p1 8 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: 8
+ -> 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 enable_indexscan to DEFAULT;
+SET parallel_setup_cost to 0;
+SET parallel_tuple_cost to 0;
+SET min_parallel_table_scan_size to 0;
+SET min_parallel_index_scan_size to 0;
SET max_parallel_workers_per_gather to 5;
EXPLAIN (COSTS false) SELECT * FROM p1;
QUERY PLAN
-> Seq Scan on p1_c3_c2
(10 rows)
+-- Errors
+/*+Parallel(p1 100x hard)Parallel(p1 -1000 hard)Parallel(p1 1000000 hard)
+ Parallel(p1 8 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(8): 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 8 soft)
+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)
+
+-- Hints on unhintable relations are just ignored
+/*+Parallel(p1 5 hard) Parallel(s1 3 hard) IndexScan(ft1) SeqScan(cte1)
+ TidScan(fs1) IndexScan(t) IndexScan(*VALUES*) */
+EXPLAIN (COSTS false) SELECT id FROM p1_c1_c1 as s1 TABLESAMPLE SYSTEM(10)
+ UNION ALL
+SELECT id FROM ft1
+ UNION ALL
+(WITH cte1 AS (SELECT id FROM p1 WHERE id % 2 = 0) SELECT id FROM cte1)
+ UNION ALL
+SELECT userid FROM pg_stat_statements fs1
+ UNION ALL
+SELECT x FROM (VALUES (1), (2), (3)) t(x);
+LOG: pg_hint_plan:
+used hint:
+Parallel(p1 5 hard)
+not used hint:
+IndexScan(*VALUES*)
+SeqScan(cte1)
+TidScan(fs1)
+IndexScan(ft1)
+IndexScan(t)
+Parallel(s1 3 hard)
+duplication hint:
+error hint:
+
+ QUERY PLAN
+-----------------------------------------------------------------------------------------------
+ Append
+ -> Result
+ -> Append
+ -> Sample Scan on p1_c1_c1 s1
+ Sampling: system ('10'::real)
+ -> Foreign Scan on ft1
+ Foreign File: /home/horiguti/work/pg_hint_plan/pg_hint_plan/data/data.csv
+ -> CTE Scan on cte1
+ CTE cte1
+ -> Gather
+ Workers Planned: 5
+ -> Append
+ -> Parallel Seq Scan on p1
+ Filter: ((id % 2) = 0)
+ -> Parallel Seq Scan on p1_c1
+ Filter: ((id % 2) = 0)
+ -> Parallel Seq Scan on p1_c2
+ Filter: ((id % 2) = 0)
+ -> Parallel Seq Scan on p1_c3
+ Filter: ((id % 2) = 0)
+ -> Parallel Seq Scan on p1_c4
+ Filter: ((id % 2) = 0)
+ -> Parallel Seq Scan on p1_c1_c1
+ Filter: ((id % 2) = 0)
+ -> Parallel Seq Scan on p1_c1_c2
+ Filter: ((id % 2) = 0)
+ -> Parallel Seq Scan on p1_c3_c1
+ Filter: ((id % 2) = 0)
+ -> Parallel Seq Scan on p1_c3_c2
+ Filter: ((id % 2) = 0)
+ -> Function Scan on pg_stat_statements
+ -> Subquery Scan on "*SELECT* 5"
+ -> Values Scan on "*VALUES*"
+(33 rows)
+
ALTER SYSTEM SET session_preload_libraries TO DEFAULT;
SELECT pg_reload_conf();
pg_reload_conf
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