Lateral View用于把UDTF的行转列结果集合在一起提供服务。Lateral View可以返回多列数据，前提是UDTF注册的输出个数。 UDTF代码参考：hive/src/ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDTFExplode.java
准备数据
create table test_array (a array<int>, b array<string>)
ROW FORMAT DELIMITED
FIELDS TERMINATED BY '`'
COLLECTION ITEMS TERMINATED BY ',';测试数据，保存文件为/tmp/test
10,11`tom,mary
20,21`kate,tim
导入数据
load data local inpath '/tmp/test' overwrite into table test_array;测试
hive> select explode(b) as name, a from test_array;
FAILED: SemanticException 1:27 Only a single expression in the SELECT clause is supported with UDTF's. Error encountered near token 'a'
UDTF只能select单列 使用LATERAL VIEW
hive> SELECT a, name FROM test_array LATERAL VIEW explode(b) r1 AS name;
[10,11] tom
[10,11] mary
[20,21] kate
[20,21] tim
可以有多个lateral view
hive> SELECT id, name FROM test_array LATERAL VIEW explode(b) r1 AS name LATERAL VIEW explode(A) r2 AS id;
10 tom
11 tom
10 mary
11 mary
20 kate
21 kate
20 tim
21 tim