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|
--
-- PARALLEL
--
create or replace function parallel_restricted(int) returns int as
$$begin return $1; end$$ language plpgsql parallel restricted;
-- Serializable isolation would disable parallel query, so explicitly use an
-- arbitrary other level.
begin isolation level repeatable read;
-- encourage use of parallel plans
set parallel_setup_cost=0;
set parallel_tuple_cost=0;
set min_parallel_table_scan_size=0;
set max_parallel_workers_per_gather=4;
explain (costs off)
select count(*) from a_star;
QUERY PLAN
-----------------------------------------------------------
Finalize Aggregate
-> Remote Subquery Scan on all (datanode_1,datanode_2)
-> Gather
Workers Planned: 1
-> Partial Aggregate
-> Append
-> Parallel Seq Scan on a_star
-> Parallel Seq Scan on b_star
-> Parallel Seq Scan on c_star
-> Parallel Seq Scan on d_star
-> Parallel Seq Scan on e_star
-> Parallel Seq Scan on f_star
(12 rows)
select count(*) from a_star;
count
-------
50
(1 row)
-- test that parallel_restricted function doesn't run in worker
alter table tenk1 set (parallel_workers = 4);
explain (verbose, costs off)
select parallel_restricted(unique1) from tenk1
where stringu1 = 'GRAAAA' order by 1;
QUERY PLAN
---------------------------------------------------------------
Remote Subquery Scan on all (datanode_1,datanode_2)
Output: parallel_restricted(unique1)
Sort Key: parallel_restricted(tenk1.unique1)
-> Sort
Output: (parallel_restricted(unique1))
Sort Key: (parallel_restricted(tenk1.unique1))
-> Gather
Output: parallel_restricted(unique1)
Workers Planned: 4
-> Parallel Seq Scan on public.tenk1
Output: unique1
Filter: (tenk1.stringu1 = 'GRAAAA'::name)
(12 rows)
-- test parallel plan when group by expression is in target list.
explain (costs off)
select length(stringu1) from tenk1 group by length(stringu1);
QUERY PLAN
-----------------------------------------------------------
Finalize HashAggregate
Group Key: length((stringu1)::text)
-> Remote Subquery Scan on all (datanode_1,datanode_2)
-> Gather
Workers Planned: 4
-> Partial HashAggregate
Group Key: length((stringu1)::text)
-> Parallel Seq Scan on tenk1
(8 rows)
select length(stringu1) from tenk1 group by length(stringu1);
length
--------
6
(1 row)
explain (costs off)
select stringu1, count(*) from tenk1 group by stringu1 order by stringu1;
QUERY PLAN
-----------------------------------------------------------
Finalize GroupAggregate
Group Key: stringu1
-> Remote Subquery Scan on all (datanode_1,datanode_2)
-> Sort
Sort Key: stringu1
-> Partial HashAggregate
Group Key: stringu1
-> Gather
Workers Planned: 4
-> Parallel Seq Scan on tenk1
(10 rows)
-- test that parallel plan for aggregates is not selected when
-- target list contains parallel restricted clause.
explain (costs off)
select sum(parallel_restricted(unique1)) from tenk1
group by(parallel_restricted(unique1));
QUERY PLAN
-------------------------------------------------------------------------
HashAggregate
Group Key: parallel_restricted(unique1)
-> Remote Subquery Scan on all (datanode_1,datanode_2)
-> Gather
Workers Planned: 4
-> Parallel Index Only Scan using tenk1_unique1 on tenk1
(6 rows)
-- test parallel plans for queries containing un-correlated subplans.
alter table tenk2 set (parallel_workers = 0);
explain (costs off)
select count(*) from tenk1 where (two, four) not in
(select hundred, thousand from tenk2 where thousand > 100);
QUERY PLAN
-------------------------------------------------------------------------------------
Finalize Aggregate
-> Remote Subquery Scan on all (datanode_1,datanode_2)
-> Gather
Workers Planned: 4
-> Partial Aggregate
-> Parallel Seq Scan on tenk1
Filter: (NOT (hashed SubPlan 1))
SubPlan 1
-> Remote Subquery Scan on all (datanode_1,datanode_2)
-> Seq Scan on tenk2
Filter: (thousand > 100)
(11 rows)
select count(*) from tenk1 where (two, four) not in
(select hundred, thousand from tenk2 where thousand > 100);
count
-------
10000
(1 row)
-- this is not parallel-safe due to use of random() within SubLink's testexpr:
explain (costs off)
select * from tenk1 where (unique1 + random())::integer not in
(select ten from tenk2);
QUERY PLAN
-------------------------------------------------------------------
Remote Subquery Scan on all (datanode_1,datanode_2)
-> Seq Scan on tenk1
Filter: (NOT (hashed SubPlan 1))
SubPlan 1
-> Remote Subquery Scan on all (datanode_1,datanode_2)
-> Seq Scan on tenk2
(6 rows)
alter table tenk2 reset (parallel_workers);
-- test parallel index scans.
set enable_seqscan to off;
set enable_bitmapscan to off;
explain (costs off)
select count((unique1)) from tenk1 where hundred > 1;
QUERY PLAN
--------------------------------------------------------------------------
Finalize Aggregate
-> Remote Subquery Scan on all (datanode_1,datanode_2)
-> Gather
Workers Planned: 4
-> Partial Aggregate
-> Parallel Index Scan using tenk1_hundred on tenk1
Index Cond: (hundred > 1)
(7 rows)
select count((unique1)) from tenk1 where hundred > 1;
count
-------
9800
(1 row)
-- test parallel index-only scans.
explain (costs off)
select count(*) from tenk1 where thousand > 95;
QUERY PLAN
--------------------------------------------------------------------------------------
Finalize Aggregate
-> Remote Subquery Scan on all (datanode_1,datanode_2)
-> Gather
Workers Planned: 4
-> Partial Aggregate
-> Parallel Index Only Scan using tenk1_thous_tenthous on tenk1
Index Cond: (thousand > 95)
(7 rows)
select count(*) from tenk1 where thousand > 95;
count
-------
9040
(1 row)
reset enable_seqscan;
reset enable_bitmapscan;
-- test parallel bitmap heap scan.
set enable_seqscan to off;
set enable_indexscan to off;
set enable_hashjoin to off;
set enable_mergejoin to off;
set enable_material to off;
-- test prefetching, if the platform allows it
--DO $$
--BEGIN
-- SET effective_io_concurrency = 50;
--END $$;
set work_mem='64kB'; --set small work mem to force lossy pages
explain (costs off)
select count(*) from tenk1, tenk2 where tenk1.hundred > 1 and tenk2.thousand=0;
QUERY PLAN
------------------------------------------------------------------------
Aggregate
-> Nested Loop
-> Remote Subquery Scan on all (datanode_1,datanode_2)
-> Seq Scan on tenk2
Filter: (thousand = 0)
-> Materialize
-> Remote Subquery Scan on all (datanode_1,datanode_2)
-> Gather
Workers Planned: 4
-> Parallel Bitmap Heap Scan on tenk1
Recheck Cond: (hundred > 1)
-> Bitmap Index Scan on tenk1_hundred
Index Cond: (hundred > 1)
(13 rows)
select count(*) from tenk1, tenk2 where tenk1.hundred > 1 and tenk2.thousand=0;
count
-------
98000
(1 row)
create table bmscantest (a int, t text);
insert into bmscantest select r, 'fooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo' FROM generate_series(1,100000) r;
create index i_bmtest ON bmscantest(a);
select count(*) from bmscantest where a>1;
count
-------
99999
(1 row)
reset enable_seqscan;
reset enable_indexscan;
reset enable_hashjoin;
reset enable_mergejoin;
reset enable_material;
reset effective_io_concurrency;
reset work_mem;
drop table bmscantest;
-- test parallel merge join path.
set enable_hashjoin to off;
set enable_nestloop to off;
explain (costs off)
select count(*) from tenk1, tenk2 where tenk1.unique1 = tenk2.unique1;
QUERY PLAN
-------------------------------------------------------------------------------------
Finalize Aggregate
-> Remote Subquery Scan on all (datanode_1,datanode_2)
-> Gather
Workers Planned: 4
-> Partial Aggregate
-> Merge Join
Merge Cond: (tenk1.unique1 = tenk2.unique1)
-> Parallel Index Only Scan using tenk1_unique1 on tenk1
-> Index Only Scan using tenk2_unique1 on tenk2
(9 rows)
select count(*) from tenk1, tenk2 where tenk1.unique1 = tenk2.unique1;
count
-------
10000
(1 row)
reset enable_hashjoin;
reset enable_nestloop;
--test gather merge
set enable_hashagg to off;
explain (costs off)
select string4, count((unique2)) from tenk1 group by string4 order by string4;
QUERY PLAN
-----------------------------------------------------------
Finalize GroupAggregate
Group Key: string4
-> Remote Subquery Scan on all (datanode_1,datanode_2)
-> Gather Merge
Workers Planned: 4
-> Partial GroupAggregate
Group Key: string4
-> Sort
Sort Key: string4
-> Parallel Seq Scan on tenk1
(10 rows)
select string4, count((unique2)) from tenk1 group by string4 order by string4;
string4 | count
---------+-------
AAAAxx | 2500
HHHHxx | 2500
OOOOxx | 2500
VVVVxx | 2500
(4 rows)
reset enable_hashagg;
set force_parallel_mode=1;
explain (costs off)
select stringu1::int2 from tenk1 where unique1 = 1;
QUERY PLAN
-----------------------------------------------------
Remote Fast Query Execution
Node/s: datanode_1
-> Gather
Workers Planned: 1
Single Copy: true
-> Index Scan using tenk1_unique1 on tenk1
Index Cond: (unique1 = 1)
(7 rows)
-- to increase the parallel query test coverage
EXPLAIN (timing off, summary off, costs off) SELECT * FROM tenk1;
QUERY PLAN
----------------------------------------
Remote Fast Query Execution
Node/s: datanode_1, datanode_2
-> Gather
Workers Planned: 4
-> Parallel Seq Scan on tenk1
(5 rows)
EXPLAIN (analyze, timing off, summary off, costs off) SELECT * FROM tenk1;
QUERY PLAN
---------------------------------------------------------
Remote Fast Query Execution (actual rows=10000 loops=1)
Node/s: datanode_1, datanode_2
(2 rows)
-- provoke error in worker
select stringu1::int2 from tenk1 where unique1 = 1;
ERROR: invalid input syntax for integer: "BAAAAA"
CONTEXT: parallel worker
rollback;
|