postgresql-int,bigint,numeric效率测试

在postgresql9.5的时候做过一个测试就是sum()的效率最终的测试结果是sum(int)>sum(numeric)>sum(bigint)当时比较诧异为啥sum(bigint)效率比sum(numeric)还低。sum(numeric)的效率比sum(bigint)快了10%。

在pg10版本的时候对sum()的性能做了优化，pg10.4

最终的测试结果为pg10的效率大幅提升，sum(int)>sum(bigint)>sum(numeric)，当一个表中有bigint，int时，谁放在第一列效率要高点。但是差别不是很大，效率都比numeric高。

 

bigint for smallint or int arguments, numeric for bigint arguments, otherwise the same as the argument data type

这次主要做abase5.0测试，以及pg11 jit测试。

插入1kw数据测试。

这里只是输出类型的转换，并不会太影响效率。

numeric的算术运算比整数类型要慢很多。

通过求助，最终了解到可能和pg的元组变形(tuple deform)有关,

这次创建三张表分别对应三种数据类型。

create table t_int(n_int int);

create table t_bigint(n_bigint bigint);

create table t_numeric(n_numeric numeric);

insert into t_int select generate_series(1,10000000);

insert into t_bigint select generate_series(1,10000000);

insert into t_numeric select generate_series(1,10000000);

 

https://blog.csdn.net/luojinbai/article/details/42914299

 

numeric :https://explain.depesz.com/s/Lk6P

int:https://explain.depesz.com/s/4Xo4

bigint:https://explain.depesz.com/s/niQI

 

pg:bigint,numeric,int效率测试：

drop table t_int;

drop table t_bigint;

drop table t_numeric;

show shared_buffers;

 

drop table t_bigint

create table t_int(n_int int);

create table t_bigint(n_bigint bigint);

create table t_numeric(n_numeric numeric);

insert into t_int select generate_series(1,10000000);

insert into t_bigint select generate_series(1,10000000);

insert into t_numeric select generate_series(1,10000000);

numeric

https://explain.depesz.com/s/Ivks

select version();

explain analyze

select count(*) from t_num_type

 

SET max_parallel_workers_per_gather = 2;

show max_parallel_workers_per_gather ;

 

select version();

1.单表测试

explain (analyze,buffers,format text) select sum(n_int) from t_int;--560

explain (analyze,buffers,format text) select sum(n_bigint) from t_bigint;--575

explain (analyze,buffers,format text) select sum(n_numeric) from t_numeric;--868

sum(int)>sum(bigint)>sum(numeric)

2.一个表测试

drop table t_num_type

create table t_num_type(n_bigint bigint,n_numeric numeric,n_int int);

insert into t_num_type select n,n,n from generate_series(1,10000000) as t(n)

explain (analyze,buffers,format text) select sum(n_int) from t_num_type ;--661

explain (analyze,buffers,format text) select sum(n_bigint) from t_num_type;--625

explain (analyze,buffers,format text) select sum(n_numeric) from t_num_type;--946

 

sum(bigint)>sum(int)>sum(numeric)

但是整体比单表慢。

select * from t_num_type_3 limit 10

 

drop table t_num_type_2

create table t_num_type_2(n_int int,n_numeric numeric,n_bigint bigint);

insert into t_num_type_2 select n,n,n from generate_series(1,10000000) as t(n)

explain (analyze,buffers,format text) select sum(n_int) from t_num_type_2;--603

explain (analyze,buffers,format text) select sum(n_bigint) from t_num_type_2;--668

explain (analyze,buffers,format text) select sum(n_numeric) from t_num_type_2;--947

sum(int)>sum(bigint)>sum(numeric)

--show jit_above_cost

int放前面int快，bigint又慢了。

 

3.

create table t_num_type_3(n_bigint bigint,n_int int,n_numeric numeric);

insert into t_num_type_3 select n,n,n from generate_series(1,10000000) as t(n)

explain (analyze,buffers,format text) select sum(n_int) from t_num_type_3;--623

explain (analyze,buffers,format text) select sum(n_bigint) from t_num_type_3;--616

explain (analyze,buffers,format text) select sum(n_numeric) from t_num_type_3;--973

 

目前来bigint放到第一列总是快的。当int放到第一列的时候又比bigint快。

 

 

create table t_num_type_4(n_int int,n_bigint bigint,n_numeric numeric);

insert into t_num_type_4 select n,n,n from generate_series(1,10000000) as t(n)

explain (analyze,buffers,format text) select sum(n_int) from t_num_type_4;--617

explain (analyze,buffers,format text) select sum(n_bigint) from t_num_type_4;--643

explain (analyze,buffers,format text) select sum(n_numeric) from t_num_type_4;--973