SET parallel_setup_cost to 0;
SET parallel_tuple_cost to 0;
-SET min_parallel_relation_size 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;
-> Parallel Seq Scan on t1
(3 rows)
+/*+Parallel(t1 4 hard) */ /* to be gather merge*/
+EXPLAIN (COSTS false) SELECT * FROM s1.t1 ORDER BY s1.t1.c1 LIMIT 4;
+LOG: pg_hint_plan:
+used hint:
+Parallel(t1 4 hard)
+not used hint:
+duplication hint:
+error hint:
+
+ QUERY PLAN
+---------------------------------------------------
+ Limit
+ -> Gather Merge
+ Workers Planned: 4
+ -> Parallel Index Scan using t1_i1 on t1
+(4 rows)
+
-- Queries on inheritance tables
SET parallel_setup_cost to 0;
SET parallel_tuple_cost to 0;
-SET min_parallel_relation_size to 0;
+SET min_parallel_table_scan_size to 0;
+SET min_parallel_index_scan_size to 0;
+SET enable_parallel_append to false;
/*+Parallel(p1 8)*/
EXPLAIN (COSTS false) SELECT * FROM p1;
LOG: pg_hint_plan:
-> Parallel Seq Scan on p1_c3_c2
(12 rows)
+SET enable_parallel_append to true;
+/*+Parallel(p1 8)*/
+EXPLAIN (COSTS false) SELECT * FROM p1;
+LOG: pg_hint_plan:
+used hint:
+Parallel(p1 8 soft)
+not used hint:
+duplication hint:
+error hint:
+
+ QUERY PLAN
+-------------------------------------------
+ Gather
+ Workers Planned: 2
+ -> Parallel Append
+ -> Seq Scan on p1
+ -> Seq Scan on p1_c1
+ -> Seq Scan on p1_c3
+ -> Parallel Seq Scan on p1_c2
+ -> 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;
+SET min_parallel_table_scan_size to DEFAULT;
+SET min_parallel_index_scan_size to DEFAULT;
+SET enable_parallel_append to false;
/*+Parallel(p1 8 hard)*/
EXPLAIN (COSTS false) SELECT * FROM p1;
LOG: pg_hint_plan:
-> Parallel Seq Scan on p1_c3_c2
(12 rows)
--- hinting on children makes the whole inheritance parallel
-/*+Parallel(p1_c1 8 hard)*/
+SET enable_parallel_append to true;
+/*+Parallel(p1 8 hard)*/
EXPLAIN (COSTS false) SELECT * FROM p1;
LOG: pg_hint_plan:
used hint:
-Parallel(p1_c1 8 hard)
+Parallel(p1 8 hard)
not used hint:
duplication hint:
error hint:
-------------------------------------------
Gather
Workers Planned: 8
- -> Append
- -> Parallel Seq Scan on p1
- -> Parallel Seq Scan on p1_c1
+ -> Parallel Append
+ -> Seq Scan on p1
+ -> Seq Scan on p1_c1
+ -> Seq Scan on p1_c3
-> 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_c2
(12 rows)
+-- hinting on children doesn't work (changed as of pg_hint_plan 10)
+SET enable_parallel_append to false;
+/*+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
+----------------------------
+ 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)
+
+SET enable_parallel_append to true;
+/*+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
+----------------------------
+ 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)
+
-- Joins
EXPLAIN (COSTS false) SELECT * FROM p1_c1_c1 join p2_c1_c1 on p1_c1_c1.id = p2_c1_c1.id;
QUERY PLAN
SET parallel_setup_cost to 0;
SET parallel_tuple_cost to 0;
-SET min_parallel_relation_size 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:
QUERY PLAN
-------------------------------------------------
- Hash Join
- Hash Cond: (p1_c1_c1.id = p2_c1_c1.id)
- -> Gather
- Workers Planned: 8
+ Gather
+ Workers Planned: 8
+ -> Parallel Hash Join
+ Hash Cond: (p1_c1_c1.id = p2_c1_c1.id)
-> Parallel Seq Scan on p1_c1_c1
- -> Hash
- -> Gather
- Workers Planned: 8
+ -> Parallel Hash
-> Parallel Seq Scan on p2_c1_c1
-(9 rows)
+(7 rows)
-- Joins on inheritance tables
SET parallel_setup_cost to 0;
SET parallel_tuple_cost to 0;
-SET min_parallel_relation_size to 0;
+SET min_parallel_table_scan_size to 0;
+SET min_parallel_index_scan_size to 0;
+SET enable_parallel_append to false;
/*+Parallel(p1 8)*/
EXPLAIN (COSTS false) SELECT * FROM p1 join p2 on p1.id = p2.id;
LOG: pg_hint_plan:
QUERY PLAN
-------------------------------------------------------
- Hash Join
- Hash Cond: (p1.id = p2.id)
- -> Gather
- Workers Planned: 1
+ Gather
+ Workers Planned: 1
+ -> Parallel 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_c1_c2
-> Parallel Seq Scan on p1_c3_c1
-> Parallel Seq Scan on p1_c3_c2
- -> Hash
- -> Gather
- Workers Planned: 1
+ -> Parallel Hash
-> Append
-> Parallel Seq Scan on p2
-> Parallel Seq Scan on p2_c1
-> Parallel Seq Scan on p2_c1_c2
-> Parallel Seq Scan on p2_c3_c1
-> Parallel Seq Scan on p2_c3_c2
-(27 rows)
+(25 rows)
+SET enable_parallel_append to true;
+/*+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: 2
+ -> Parallel Hash Join
+ Hash Cond: (p1.id = p2.id)
+ -> Parallel Append
+ -> Seq Scan on p1
+ -> Seq Scan on p1_c1
+ -> Seq Scan on p1_c3
+ -> Parallel Seq Scan on p1_c2
+ -> 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 Hash
+ -> Parallel Append
+ -> Seq Scan on p2
+ -> Seq Scan on p2_c1
+ -> Seq Scan on p2_c3
+ -> Parallel Seq Scan on p2_c2
+ -> 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
+(25 rows)
+
+SET enable_parallel_append to false;
/*+Parallel(p1 8)Parallel(p2 0)*/
EXPLAIN (COSTS false) SELECT * FROM p1 join p2 on p1.id = p2.id;
LOG: pg_hint_plan:
-> Seq Scan on p2_c3_c2
(25 rows)
+SET enable_parallel_append to true;
+/*+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 8 soft)
+Parallel(p2 0 soft)
+not used hint:
+duplication hint:
+error hint:
+
+ QUERY PLAN
+-------------------------------------------------
+ Gather
+ Workers Planned: 2
+ -> Parallel Hash Join
+ Hash Cond: (p1.id = p2_c2.id)
+ -> Parallel Append
+ -> Seq Scan on p1
+ -> Seq Scan on p1_c1
+ -> Seq Scan on p1_c3
+ -> Parallel Seq Scan on p1_c2
+ -> 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 Hash
+ -> Parallel Append
+ -> Seq Scan on p2_c2
+ -> 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
+ -> Seq Scan on p2
+ -> Seq Scan on p2_c1
+ -> Seq Scan on p2_c3
+(25 rows)
+
SET parallel_setup_cost to DEFAULT;
SET parallel_tuple_cost to DEFAULT;
-SET min_parallel_relation_size 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:
duplication hint:
error hint:
- QUERY PLAN
--------------------------------------------------
+ QUERY PLAN
+----------------------------------------
Hash Join
- Hash Cond: (p2.id = p1.id)
- -> 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
+ Hash Cond: (p1.id = p2.id)
+ -> 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
-> 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)
+ -> 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(p2 8 hard)*/
EXPLAIN (COSTS false) SELECT * FROM p1 join p2 on p1.id = p2.id;
duplication hint:
error hint:
- QUERY PLAN
--------------------------------------------------
- Hash Join
- Hash Cond: (p2.id = p1.id)
- -> Gather
- Workers Planned: 8
- -> Append
- -> Parallel Seq Scan on p2
- -> Parallel Seq Scan on p2_c1
+ QUERY PLAN
+-------------------------------------------------------
+ Gather
+ Workers Planned: 8
+ -> Parallel Hash Join
+ Hash Cond: (p2.id = p1.id)
+ -> Parallel Append
+ -> Seq Scan on p2
+ -> Seq Scan on p2_c1
+ -> Seq Scan on p2_c3
-> 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
+ -> Parallel Hash
+ -> Parallel Append
+ -> Seq Scan on p1
+ -> Seq Scan on p1_c1
+ -> Seq Scan on p1_c3
+ -> Parallel Seq Scan on p1_c2
+ -> 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)
+-- Number of workers results to the largest number
+SET enable_parallel_append to false;
/*+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:
QUERY PLAN
-------------------------------------------------------
- Hash Join
- Hash Cond: (p2.id = p1.id)
- -> Gather
- Workers Planned: 8
+ Gather
+ Workers Planned: 8
+ -> Parallel Hash Join
+ Hash Cond: (p1.id = p2.id)
-> Append
- -> Parallel Seq Scan on p2
- -> Parallel Seq Scan on p2_c1
+ -> 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 Hash
+ -> 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
+(25 rows)
+
+SET enable_parallel_append to true;
+/*+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 8 hard)
+not used hint:
+duplication hint:
+error hint:
+
+ QUERY PLAN
+-------------------------------------------------------
+ Gather
+ Workers Planned: 8
+ -> Parallel Hash Join
+ Hash Cond: (p2.id = p1.id)
+ -> Parallel Append
+ -> Seq Scan on p2
+ -> Seq Scan on p2_c1
+ -> Seq Scan on p2_c3
-> 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
+ -> Parallel Hash
+ -> Parallel Append
+ -> Seq Scan on p1
+ -> Seq Scan on p1_c1
+ -> Seq Scan on p1_c3
+ -> Parallel Seq Scan on p1_c2
+ -> 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)
+
+-- Mixture with scan hints
+-- p1 can be parallel
+SET enable_parallel_append to false;
+/*+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: 5
+ Workers Planned: 8
-> Append
-> Parallel Seq Scan on p1
-> Parallel Seq Scan on p1_c1
-> Parallel Seq Scan on p1_c1_c2
-> Parallel Seq Scan on p1_c3_c1
-> Parallel Seq Scan on p1_c3_c2
-(27 rows)
+(25 rows)
--- Mixture with a scan hint
--- p1 can be parallel
+SET enable_parallel_append to true;
/*+Parallel(p1 8 hard) IndexScan(p2) */
EXPLAIN (COSTS false) SELECT * FROM p1 join p2 on p1.id = p2.id;
LOG: pg_hint_plan:
-> Hash
-> Gather
Workers Planned: 8
- -> Append
- -> Parallel Seq Scan on p1
- -> Parallel Seq Scan on p1_c1
+ -> Parallel Append
+ -> Seq Scan on p1
+ -> Seq Scan on p1_c1
+ -> Seq Scan on p1_c3
-> 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_c2
(25 rows)
--- seqscan doesn't harm parallelism
+-- Parallel sequential scan
+SET enable_parallel_append to false;
/*+Parallel(p1 8 hard) SeqScan(p1) */
EXPLAIN (COSTS false) SELECT * FROM p1 join p2 on p1.id = p2.id;
LOG: pg_hint_plan:
duplication hint:
error hint:
- QUERY PLAN
--------------------------------------------------
- Hash Join
- Hash Cond: (p1.id = p2.id)
- -> Gather
- Workers Planned: 8
+ QUERY PLAN
+-------------------------------------------------------
+ Gather
+ Workers Planned: 8
+ -> Parallel 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_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
+ -> Parallel Hash
+ -> 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
+(25 rows)
+
+SET enable_parallel_append to true;
+/*+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
+ -> Parallel Hash Join
+ Hash Cond: (p1.id = p2.id)
+ -> Parallel Append
+ -> Seq Scan on p1
+ -> Seq Scan on p1_c1
+ -> Seq Scan on p1_c3
+ -> Parallel Seq Scan on p1_c2
+ -> 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 Hash
+ -> Parallel Append
+ -> Seq Scan on p2
+ -> Seq Scan on p2_c1
+ -> Seq Scan on p2_c3
+ -> Parallel Seq Scan on p2_c2
+ -> 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
(25 rows)
--- we don't have parallel over index scans so far
+-- Parallel index scan
+SET enable_parallel_append to false;
/*+Parallel(p1 8 hard) IndexScan(p1) */
EXPLAIN (COSTS false) SELECT * FROM p1 join p2 on p1.id = p2.id;
LOG: pg_hint_plan:
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
+ QUERY PLAN
+-----------------------------------------------------------------------
+ Gather
+ Workers Planned: 8
+ -> Parallel Hash Join
+ Hash Cond: (p1.id = p2.id)
-> 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 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
+ -> Parallel Hash
+ -> 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
+(25 rows)
+
+SET enable_parallel_append to true;
+/*+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
+ -> Parallel Hash Join
+ Hash Cond: (p1.id = p2.id)
+ -> Parallel 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
+ -> Parallel Hash
+ -> Parallel Append
+ -> Seq Scan on p2
+ -> Seq Scan on p2_c1
+ -> Seq Scan on p2_c3
+ -> Parallel Seq Scan on p2_c2
+ -> 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
+(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)
-Parallel(p1 0 hard)
not used hint:
+Parallel(p1 0 hard)
duplication hint:
error hint:
-- parallel hinting on any relation enables parallel
SET parallel_setup_cost to 0;
SET parallel_tuple_cost to 0;
-SET min_parallel_relation_size 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;
-------------------------------------------
Gather
Workers Planned: 1
- -> Append
+ -> Parallel Append
+ -> Parallel Seq Scan on p2_c2
+ -> 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
-> Parallel Seq Scan on p1
-> Parallel Seq Scan on p1_c1
-> Parallel Seq Scan on p1_c2
-> 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 hint has the same effect
/*+Set(max_parallel_workers_per_gather 1)*/
EXPLAIN (COSTS false) SELECT id FROM p1 UNION ALL SELECT id FROM p2;
LOG: pg_hint_plan:
-------------------------------------------
Gather
Workers Planned: 1
- -> Append
- -> Parallel Seq Scan on p1
- -> Parallel Seq Scan on p1_c1
+ -> Parallel Append
-> Parallel Seq Scan on p1_c2
- -> Parallel Seq Scan on p1_c3
-> Parallel Seq Scan on p1_c4
+ -> Parallel Seq Scan on p2_c2
+ -> Parallel Seq Scan on p2_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
+ -> Parallel Seq Scan on p1
+ -> Parallel Seq Scan on p1_c1
+ -> Parallel Seq Scan on p1_c3
+ -> Parallel Seq Scan on p2
+ -> Parallel Seq Scan on p2_c1
+ -> Parallel Seq Scan on p2_c3
(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_relation_size 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;
-------------------------------------------
Gather
Workers Planned: 6
- -> Append
- -> Parallel Seq Scan on p1
- -> Parallel Seq Scan on p1_c1
+ -> Parallel Append
+ -> Seq Scan on p1
+ -> Seq Scan on p1_c1
+ -> Seq Scan on p1_c3
+ -> Seq Scan on p2
+ -> Seq Scan on p2_c1
+ -> Seq Scan on p2_c3
-> 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_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;
-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
+-- Negative hints
SET enable_indexscan to DEFAULT;
SET parallel_setup_cost to 0;
SET parallel_tuple_cost to 0;
-SET min_parallel_relation_size 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
-------------------------------------------
Gather
- Workers Planned: 1
- -> Append
- -> Parallel Seq Scan on p1
- -> Parallel Seq Scan on p1_c1
+ Workers Planned: 4
+ -> Parallel Append
-> 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 p1
+ -> Parallel Seq Scan on p1_c1
+ -> Parallel Seq Scan on p1_c3
(12 rows)
+SET enable_parallel_append to false;
+/*+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)
+
+SET enable_parallel_append to true;
/*+Parallel(p1 0 hard)*/
EXPLAIN (COSTS false) SELECT * FROM p1;
LOG: pg_hint_plan:
-------------------------------------------
Gather
Workers Planned: 1
- -> Append
- -> Parallel Seq Scan on p1
- -> Parallel Seq Scan on p1_c1
+ -> Parallel Append
-> Parallel Seq Scan on p1_c2
- -> Parallel Seq Scan on p1_c3
-> Parallel Seq Scan on p1_c4
+ -> Parallel Seq Scan on p2_c2
+ -> Parallel Seq Scan on p2_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
+ -> Parallel Seq Scan on p1
+ -> Parallel Seq Scan on p1_c1
+ -> Parallel Seq Scan on p1_c3
+ -> Parallel Seq Scan on p2
+ -> Parallel Seq Scan on p2_c1
+ -> Parallel Seq Scan on p2_c3
(21 rows)
-- Hints on unhintable relations are just ignored
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)
+ -> Gather
+ Workers Planned: 5
+ -> Parallel Append
+ -> Seq Scan on p1
+ Filter: ((id % 2) = 0)
+ -> Seq Scan on p1_c1
+ Filter: ((id % 2) = 0)
+ -> Seq Scan on p1_c3
+ Filter: ((id % 2) = 0)
+ -> Parallel Seq Scan on p1_c2
+ 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)
+(31 rows)
ALTER SYSTEM SET session_preload_libraries TO DEFAULT;
SELECT pg_reload_conf();