Hive 優(yōu)化階段 map join 優(yōu)化，我用我們公司的測試集群跑了一下，執(zhí)行的時間如下，供大家參考

------------------ MAP JOIN 測試
set hive.execution.engine=mr;

--- 未開啟 MAP JOIN
--- execution: 3 m 48 s 547 ms, fetching: 234 ms
set hive.auto.convert.join=false;
select *
from order_detail od
         join product_info product on od.product_id = product.id
         join province_info province on od.province_id = province.id;


--- 方案一：開啟 map join
set hive.auto.convert.join=true;
set hive.auto.convert.join.noconditionaltask=false;
set hive.mapjoin.smalltable.filesize=25285707;
--- execution: 3 m 59 s 70 ms, fetching: 201 ms
select *
from order_detail od
         join product_info product on od.product_id = product.id
         join province_info province on od.province_id = province.id;


-- 方案二：開啟 map join
set hive.auto.convert.join=true;
set hive.auto.convert.join.noconditionaltask=true;
set hive.auto.convert.join.noconditionaltask.size=25286076;
-- execution: 1 m 28 s 499 ms, fetching: 151 ms
select *
from order_detail od
         join product_info product on od.product_id = product.id
         join province_info province on od.province_id = province.id;


-- 方案三：開啟 map join
set hive.auto.convert.join=true;
set hive.auto.convert.join.noconditionaltask=true;
set hive.auto.convert.join.noconditionaltask.size=25285707;
-- execution: 3 m 26 s 115 ms, fetching: 165 ms
select *
from order_detail od
         join product_info product on od.product_id = product.id
         join province_info province on od.province_id = province.id;