关注my question 我有以下表格，第一个（范围）包括值范围和其他列：
row | From | To | Country ....
-----|--------|---------|---------
1 | 1200 | 1500 |
2 | 2200 | 2700 |
3 | 1700 | 1900 |
4 | 2100 | 2150 |
...
From和To是bigint并且是独占的。 Range表包含1.8M记录。附加表（值）包含2.7M记录，如下所示：
row | Value | More columns....
--------|--------|----------------
1 | 1777 |
2 | 2122 |
3 | 1832 |
4 | 1340 |
...
我想创建一个表如下：
row | Value | From | To | More columns....
--------|--------|--------|-------|---
1 | 1777 | 1700 | 1900 |
2 | 2122 | 2100 | 2150 |
3 | 1832 | 1700 | 1900 |
4 | 1340 | 1200 | 1500 |
...
我在以下代码中使用了左外连接：
set n=1000;
select v.id
,v.val
,r.from_val
,r.to_val
from val v
left outer join
(select r.*
,floor(from_val/${hiveconf:n}) + pe.i as match_val
from val_range r
lateral view posexplode
(
split
(
space
(
cast
(
floor(to_val/${hiveconf:n})
- floor(from_val/${hiveconf:n})
as int
)
)
,' '
)
) pe as i,x
) r
on floor(v.val/${hiveconf:n}) =
r.match_val
where v.val between r.from_val and r.to_val
order by v.id
;
然而，新表的记录数量大幅减少~2.7万条记录中的记录数量。如果我使用left outer join怎么办？我该如何解决？
答案 0 :(得分：1)
假设我们有v.id
set n=1000;
select v.id
,r.from_val
,r.to_val
from val v
left join (select v.id
,r.from_val
,r.to_val
from val v
join (...) r
on floor(v.val/${hiveconf:n}) =
r.match_val
where v.val between r.from_val and r.to_val
) r
on r.id =
v.id
order by v.id
对于OP请求，以下是完整查询：
set n=1000;
select v.id
,r.from_val
,r.to_val
from val v
left join (select v.id
,r.from_val
,r.to_val
from val v
join (select r.*
,floor(from_val/${hiveconf:n}) + pe.i as match_val
from val_range r
lateral view posexplode
(
split
(
space
(
cast
(
floor(to_val/${hiveconf:n})
- floor(from_val/${hiveconf:n})
as int
)
)
,' '
)
) pe as i,x
) r
on floor(v.val/${hiveconf:n}) =
r.match_val
where v.val between r.from_val and r.to_val
) r
on r.id =
v.id
order by v.id