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HTAP数据库 PostgreSQL 场景与性能测试之 26 - (OLTP) NOT IN、NOT EXISTS 查询

标签

PostgreSQL , HTAP , OLTP , OLAP , 场景与性能测试

背景

PostgreSQL是一个历史悠久的数据库，历史可以追溯到1973年，最早由2014计算机图灵奖得主，关系数据库的鼻祖Michael_Stonebraker 操刀设计，PostgreSQL具备与Oracle类似的功能、性能、架构以及稳定性。

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PostgreSQL社区的贡献者众多，来自全球各个行业，历经数年，PostgreSQL 每年发布一个大版本，以持久的生命力和稳定性着称。

2017年10月，PostgreSQL 推出10 版本，携带诸多惊天特性，目标是胜任OLAP和OLTP的HTAP混合场景的需求：

《最受开发者欢迎的HTAP数据库PostgreSQL 10特性》

1、多核并行增强

2、fdw 聚合下推

3、逻辑订阅

4、分区

5、金融级多副本

6、json、jsonb全文检索

7、还有插件化形式存在的特性，如 向量计算、JIT、SQL图计算、SQL流计算、分布式并行计算、时序处理、基因测序、化学分析、图像分析 等。

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在各种应用场景中都可以看到PostgreSQL的应用：

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PostgreSQL近年来的发展非常迅猛，从知名数据库评测网站dbranking的数据库评分趋势，可以看到PostgreSQL向上发展的趋势：

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从每年PostgreSQL中国召开的社区会议，也能看到同样的趋势，参与的公司越来越多，分享的公司越来越多，分享的主题越来越丰富，横跨了 传统企业、互联网、医疗、金融、国企、物流、电商、社交、车联网、共享XX、云、游戏、公共交通、航空、铁路、军工、培训、咨询服务等 行业。

接下来的一系列文章，将给大家介绍PostgreSQL的各种应用场景以及对应的性能指标。

环境

环境部署方法参考：

《PostgreSQL 10 + PostGIS + Sharding(pg_pathman) + MySQL(fdw外部表) on ECS 部署指南(适合新用户)》

阿里云 ECS：56核，224G，1.5TB*2 SSD云盘。

操作系统：CentOS 7.4 x64

数据库版本：PostgreSQL 10

PS：ECS的CPU和IO性能相比物理机会打一定的折扣，可以按下降1倍性能来估算。跑物理主机可以按这里测试的性能乘以2来估算。

场景 - NOT IN、NOT EXISTS 查询 (OLTP)

1、背景

not in 查询，多用在排除多个输入值场景。

实际上PostgreSQL支持很多种排除多个输入值的语法。

1、not in (...)

2、not in (table or subquery or srf)

3、<> all (array)

4、not exists (select 1 from (values (),(),...) as t(id) where x.?=t.id)

5、<>? and <>? and <>? and .....

6、left join others b on (a.?=b.?) where b.* is null

7、select ? from a except select ? from b，适用于输出字段与条件字段相同的情形。

他们的执行计划分别如下，（1亿记录，排除多个输入值。）：

表越大、或Filter的值越多，使用 left join, not exist, except 的效果越好。

postgres=# explain select * from a where id not in (1,2,3,4,5);  
                          QUERY PLAN  
--------------------------------------------------------------  
 Seq Scan on a  (cost=0.00..255958.10 rows=10000001 width=45)  
   Filter: (id <> ALL ('{1,2,3,4,5}'::integer[]))  
(2 rows)  
  
postgres=# explain select * from a where id <> all (array[1,2,3,4,5]);  
                          QUERY PLAN  
--------------------------------------------------------------  
 Seq Scan on a  (cost=0.00..255958.10 rows=10000001 width=45)  
   Filter: (id <> ALL ('{1,2,3,4,5}'::integer[]))  
(2 rows)  
  
postgres=# explain select * from a where id <> all (array(select generate_series(1,10)));  
                         QUERY PLAN  
-------------------------------------------------------------  
 Seq Scan on a  (cost=5.02..318463.15 rows=9999996 width=45)  
   Filter: (id <> ALL ($0))  
   InitPlan 1 (returns $0)  
     ->  ProjectSet  (cost=0.00..5.02 rows=1000 width=4)  
           ->  Result  (cost=0.00..0.01 rows=1 width=0)  
(5 rows)  
  
postgres=# explain select * from a where id <> all (array(select id from (values (1),(2),(3),(4),(5)) t (id)));  
                             QUERY PLAN  
---------------------------------------------------------------------  
 Seq Scan on a  (cost=0.06..318458.20 rows=9999996 width=45)  
   Filter: (id <> ALL ($0))  
   InitPlan 1 (returns $0)  
     ->  Values Scan on "*VALUES*"  (cost=0.00..0.06 rows=5 width=4)  
(4 rows)  
  
postgres=# explain select * from a where id not in (select id from (values (1),(2),(3),(4),(5)) t (id));  
                             QUERY PLAN  
---------------------------------------------------------------------  
 Seq Scan on a  (cost=0.07..218458.15 rows=5000003 width=45)  
   Filter: (NOT (hashed SubPlan 1))  
   SubPlan 1  
     ->  Values Scan on "*VALUES*"  (cost=0.00..0.06 rows=5 width=4)  
(4 rows)  
  
postgres=# explain select * from a where not exists (select 1 from (values (1),(2),(3),(4),(5)) t (id) where t.id=a.id);  
                                    QUERY PLAN  
-----------------------------------------------------------------------------------  
 Merge Anti Join  (cost=0.56..301364.14 rows=10000001 width=45)  
   Merge Cond: (a.id = "*VALUES*".column1)  
   ->  Index Scan using a_pkey on a  (cost=0.43..276363.92 rows=10000006 width=45)  
   ->  Sort  (cost=0.12..0.13 rows=5 width=4)  
         Sort Key: "*VALUES*".column1  
         ->  Values Scan on "*VALUES*"  (cost=0.00..0.06 rows=5 width=4)  
(6 rows)  
  
postgres=# explain select * from a where id<>1 and id<>2 and id<>3 and id<>4 and id<>5;  
                                  QUERY PLAN  
-------------------------------------------------------------------------------  
 Seq Scan on a  (cost=0.00..318458.14 rows=10000001 width=45)  
   Filter: ((id <> 1) AND (id <> 2) AND (id <> 3) AND (id <> 4) AND (id <> 5))  
(2 rows)  
  
postgres=# explain with t1 as (select id from (values (1),(2),(3),(4),(5)) as t(id))  
                   select a.* from a left join t1 b on (a.id=b.id) where b.* is null;  
                             QUERY PLAN  
---------------------------------------------------------------------  
 Hash Left Join  (cost=0.23..230958.36 rows=50000 width=45)  
   Hash Cond: (a.id = b.id)  
   Filter: (b.* IS NULL)  
   CTE t1  
     ->  Values Scan on "*VALUES*"  (cost=0.00..0.06 rows=5 width=4)  
   ->  Seq Scan on a  (cost=0.00..193458.06 rows=10000006 width=45)  
   ->  Hash  (cost=0.10..0.10 rows=5 width=32)  
         ->  CTE Scan on t1 b  (cost=0.00..0.10 rows=5 width=32)  
(8 rows)  
  
postgres=# explain select id from a except select id from (values (1),(2),(3),(4),(5)) as t(id);  
                                          QUERY PLAN  
-----------------------------------------------------------------------------------------------  
 SetOp Except  (cost=1538166.72..1588166.78 rows=10000006 width=8)  
   ->  Sort  (cost=1538166.72..1563166.75 rows=10000011 width=8)  
         Sort Key: "*SELECT* 1".id  
         ->  Append  (cost=0.00..293458.23 rows=10000011 width=8)  
               ->  Subquery Scan on "*SELECT* 1"  (cost=0.00..293458.12 rows=10000006 width=8)  
                     ->  Seq Scan on a  (cost=0.00..193458.06 rows=10000006 width=4)  
               ->  Subquery Scan on "*SELECT* 2"  (cost=0.00..0.11 rows=5 width=8)  
                     ->  Values Scan on "*VALUES*"  (cost=0.00..0.06 rows=5 width=4)  
(8 rows)

2、设计

1亿记录，查询匹配多个输入值的性能。分别输入1,10,100,1000,10000,100000,1000000个值作为匹配条件。

1、not in (...)

2、not in (table or subquery or srf)

3、<> all (array)

4、not exists (select 1 from (values (),(),...) as t(id) where x.?=t.id)

5、<>? and <>? and <>? and .....

6、left join others b on (a.?=b.?) where b.* is null

7、select ? from a except select ? from b，适用于输出字段与条件字段相同的情形。

3、准备测试表

create table t_in_test (id int primary key, info text, crt_time timestamp);

4、准备测试函数(可选)

5、准备测试数据

insert into t_in_test select generate_series(1,100000000), md5(random()::text), clock_timestamp();

6、准备测试脚本

set parallel_setup_cost =0;  
set parallel_tuple_cost =0;  
set max_parallel_workers_per_gather =28;  
alter table t_in_test set (parallel_workers =28);

1、not in (...)

1,10,100,1000,10000,100000,1000000 个输入值的测试性能

do language plpgsql $$  
declare  
  arr text;  
  ts timestamp := clock_timestamp();  
  mx int8;  
begin  
  for i in 0..6 loop  
    mx := (1*(10^i))::int8;  
    select string_agg((random()*100000)::int::text, ',') into arr from generate_series(1, mx);  
    ts := clock_timestamp();  
    execute 'select * from t_in_test where id not in ('||arr||')';  
    raise notice '%: %', mx, clock_timestamp()-ts;  
  end loop;  
end;  
$$ ;

2、not in (table or subquery or srf)

1,10,100,1000,10000,100000,1000000 个输入值的测试性能

do language plpgsql $$  
declare  
  arr text;  
  ts timestamp := clock_timestamp();  
  mx int8;  
begin  
  for i in 0..6 loop  
    mx := (1*(10^i))::int8;  
    ts := clock_timestamp();  
    perform * from t_in_test where not id in ( select (random()*100000)::int from generate_series(1, mx) );  
    raise notice '%: %', mx, clock_timestamp()-ts;  
  end loop;  
end;  
$$ ;

3、<> all (array)

1,10,100,1000,10000,100000,1000000 个输入值的测试性能

do language plpgsql $$  
declare  
  arr int[];  
  ts timestamp := clock_timestamp();  
  mx int8;  
begin  
  for i in 0..6 loop  
    mx := (1*(10^i))::int8;  
    select array_agg((random()*100000)::int) into arr from generate_series(1, mx);  
    ts := clock_timestamp();  
    perform * from t_in_test where id <> all ( arr );  
    raise notice '%: %', mx, clock_timestamp()-ts;  
  end loop;  
end;  
$$ ;

4、not exists (select 1 from (values (),(),...) as t(id) where x.?=t.id)

1,10,100,1000,10000,100000,1000000 个输入值的测试性能

do language plpgsql $$  
declare  
  ts timestamp := clock_timestamp();  
  mx int8;  
begin  
  for i in 0..6 loop  
    mx := (1*(10^i))::int8;  
    ts := clock_timestamp();  
    perform * from t_in_test where not exists ( select 1 from ( select (random()*100000)::int id from generate_series(1,mx) ) t where t_in_test.id=t.id );  
    raise notice '%: %', mx, clock_timestamp()-ts;  
  end loop;  
end;  
$$ ;

6、left join others b on (a.?=b.?) where b.* is null

do language plpgsql $$  
declare  
  ts timestamp := clock_timestamp();  
  mx int8;  
begin  
  for i in 0..6 loop  
    mx := (1*(10^i))::int8;  
    ts := clock_timestamp();  
    perform a.* from t_in_test a left join (select (random()*100000)::int id from generate_series(1,mx)) b on (a.id=b.id) where b.* is null;  
    raise notice '%: %', mx, clock_timestamp()-ts;  
  end loop;  
end;  
$$ ;

7、select ? from a except select ? from b，适用于输出字段与条件字段相同的情形。

do language plpgsql $$  
declare  
  ts timestamp := clock_timestamp();  
  mx int8;  
begin  
  for i in 0..6 loop  
    mx := (1*(10^i))::int8;  
    ts := clock_timestamp();  
    perform a.id from t_in_test a except select (random()*100000)::int id from generate_series(1,mx);  
    raise notice '%: %', mx, clock_timestamp()-ts;  
  end loop;  
end;  
$$ ;

7、测试

1、not in (...)

1,10,100,1000,10000,100000,1000000 个输入值的测试性能

NOTICE:  1: 00:00:20.760034  
NOTICE:  10: 00:00:27.766224  
NOTICE:  100: 00:01:22.95002  
NOTICE:  1000: 00:10:16.690793  
..........  
10000开始很久也没跑出来。继续看后面其他方法的测试。

2、not in (table or subquery or srf)

1,10,100,1000,10000,100000,1000000 个输入值的测试性能

-----

3、<> all (array)

1,10,100,1000,10000,100000,1000000 个输入值的测试性能

-----

4、not exists (select 1 from (values (),(),...) as t(id) where x.?=t.id)

1,10,100,1000,10000,100000,1000000 个输入值的测试性能

NOTICE:  1: 00:00:35.253582  
NOTICE:  10: 00:00:35.256638  
NOTICE:  100: 00:00:35.164034  
NOTICE:  1000: 00:00:35.417756  
NOTICE:  10000: 00:00:35.205454  
NOTICE:  100000: 00:00:35.458987  
NOTICE:  1000000: 00:00:35.447743  
DO

6、a left join others b on (a.?=b.?) where b.* is null

1,10,100,1000,10000,100000,1000000 个输入值的测试性能

NOTICE:  1: 00:00:36.474715  
NOTICE:  10: 00:00:36.53191  
NOTICE:  100: 00:00:36.60439  
NOTICE:  1000: 00:00:36.534846  
NOTICE:  10000: 00:00:36.574136  
NOTICE:  100000: 00:00:36.519582  
NOTICE:  1000000: 00:00:37.675594  
DO

7、select ? from a except select ? from b，适用于输出字段与条件字段相同的情形。

1,10,100,1000,10000,100000,1000000 个输入值的测试性能

NOTICE:  1: 00:00:50.566741  
NOTICE:  10: 00:00:50.051715  
NOTICE:  100: 00:00:50.098839  
NOTICE:  1000: 00:00:49.966196  
NOTICE:  10000: 00:00:50.608288  
NOTICE:  100000: 00:00:50.715218  
NOTICE:  1000000: 00:00:51.794935  
DO

TPS

平均响应时间
not exists为例，1亿记录1到100万个点的排他过滤。
NOTICE: 1: 00:00:35.253582
NOTICE: 10: 00:00:35.256638
NOTICE: 100: 00:00:35.164034
NOTICE: 1000: 00:00:35.417756
NOTICE: 10000: 00:00:35.205454
NOTICE: 100000: 00:00:35.458987
NOTICE: 1000000: 00:00:35.447743
DO

参考

《PostgreSQL、Greenplum 应用案例宝典《如来神掌》 - 目录》

《数据库选型之 - 大象十八摸 - 致 架构师、开发者》

《PostgreSQL 使用 pgbench 测试 sysbench 相关case》

《数据库界的华山论剑 tpc.org》

https://www.postgresql.org/docs/10/static/pgbench.html

最后更新：2017-11-14 14:04:47

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