hive 去重数据

select 
a.mer_id
,a.goods_id
,a.goods_name
,a.goods_type
,a.serv_type
,a.price_mode
,a.push_inf
,a.mt_num
,a.cus_phone
,a.goods_desc
,a.mod_user
,a.mod_time
,a.in_time
,a.state
from hf_t_goods_inf a 
left outer join (
select mer_id,goods_id,max(mod_time) as mod_time from hf_t_goods_inf group by mer_id,goods_id) b on (a.mer_id = b.mer_id and a.goods_id = b.goods_id and a.mod_time = b.mod_time) 
where b.mer_id is not null;