spark支持的join类型有

[不定项选择题]

spark支持的join类型有

```
inner join
```
```
left outer join
```
```
right outer join
```
```
full  outer join
```

查看答案及解析

offer滚滚来~

Spark DataFrame中join与SQL很像，都有inner join, left join, right join, full join;
那么join方法如何实现不同的join类型呢？
看其原型
def join(right : DataFrame, usingColumns : Seq[String], joinType : String) : DataFrame
def join(right : DataFrame, joinExprs : Column, joinType : String) : DataFrame
可见，可以通过传入String类型的joinType来实现。
joinType可以是”inner”、“left”、“right”、“full”分别对应inner join, left join, right join, full join，默认值是”inner”，代表内连接

发表于 2019-04-09 15:37:50 回复(0)