从 TPCH 测试学习性能优化技巧之 Q9
一、 查询要求
Q9语句是查询每个国家每一年所有被定购的零件在一年中的总利润。
Q9语句的特点是:带有分组、排序、聚集、子查询操作并存的查询操作。子查询的父层查询不存在其他查询对象,是格式相对简单的子查询,但子查询自身是多表连接的查询。子查询中使用了LIKE操作符,有的查询优化器不支持对LIKE操作符进行优化。
二、 Oracle执行
Oracle编写的查询SQL语句如下:
select /*+ parallel(n) */
nation,
o_year,
sum(amount) as sum_profit
from
(
select
n_name as nation,
extract(year from o_orderdate) as o_year,
l_extendedprice * (1 - l_discount) - ps_supplycost * l_quantity as amount
from
part,
supplier,
lineitem,
partsupp,
orders,
nation
where
s_suppkey = l_suppkey
and ps_suppkey = l_suppkey
and ps_partkey = l_partkey
and p_partkey = l_partkey
and o_orderkey = l_orderkey
and s_nationkey = n_nationkey
and p_name like '%chocolate%'
) profit
group by
nation,
o_year
order by
nation,
o_year desc;
其中/*+ parallel(n) */ 是Oracle的并行查询语法,n是并行数。
脚本执行时间,单位:秒
并行数 |
1 |
2 |
4 |
8 |
12 |
Oracle |
930 |
502 |
331 |
267 |
234 |
三、 SPL优化
这里orders与lineitem主子表关联的优化原理同Q3。
SPL脚本如下:
A |
|
1 |
|
2 |
=now() |
3 |
>name="*chocolate*" |
4 |
=file(path+"nation.ctx").create().cursor(N_NATIONKEY,N_NAME).fetch().keys@i(N_NATIONKEY) |
5 |
=file(path+"part.ctx").create().cursor@m(P_PARTKEY, P_NAME;like(P_NAME, name);A1).fetch().derive@o().keys@i(P_PARTKEY) |
6 |
=file(path+"supplier.ctx").create().cursor@m(S_SUPPKEY,S_NATIONKEY;S_NATIONKEY:A4;A1).fetch().keys@i(S_SUPPKEY) |
7 |
=file(path+"partsupp.ctx").create().cursor@m(PS_PARTKEY, PS_SUPPKEY,PS_SUPPLYCOST;A5.find(PS_PARTKEY);A1) |
8 |
=A7.fetch().derive@o().keys@i(PS_PARTKEY,PS_SUPPKEY) |
9 |
=file(path+"orders.ctx").create().cursor@m(O_ORDERKEY,O_ORDERDATE;;A1) |
10 |
=file(path+"lineitem.ctx").create().news(A9,L_ORDERKEY,L_PARTKEY,L_SUPPKEY,L_QUANTITY,L_EXTENDEDPRICE,L_DISCOUNT,O_ORDERDATE;A8.find(L_PARTKEY,L_SUPPKEY)) |
11 |
=A10.join@i(L_PARTKEY:L_SUPPKEY, A8,PS_SUPPLYCOST).switch(L_SUPPKEY,A6).new(L_ORDERKEY,O_ORDERDATE,L_SUPPKEY.S_NATIONKEY.N_NAME:nation,L_EXTENDEDPRICE*(1-L_DISCOUNT)-PS_SUPPLYCOST*L_QUANTITY:profit) |
12 |
=A11.groups(nation,year(O_ORDERDATE):o_year;sum(profit)) |
13 |
=A12.sort(nation,o_year:-1) |
14 |
=now() |
15 |
=interval@s(A2,A14) |
A10中用join@i方法把外键表的字段PS_SUPPLYCOST拼到lineitem游标上,这里是个双字段主键的外键表,不能再使用在游标建立时匹配并转换的方法。
脚本执行时间,单位:秒
并行数 |
1 |
2 |
4 |
8 |
12 |
Oracle |
930 |
502 |
331 |
267 |
234 |
SPL组表 |
691 |
354 |
180 |
95 |
68 |
英文版