如何在加载后处理Pig Latin中的字段

Question

有一个包含大量列文件的大文件，我正在加载

A = LOAD '/path/to/file' USING PigStorage(',');

B = FOREACH A GENERATE $0 AS name, $1 as address, $2.. ;
C = FOREACH B FILTER BY (name is NOT NULL);

我收到投影字段[名称]不存在的错误？我不想通过做$ 0，$ 1以及所有这些来解决列。我怎样才能给他们一些标识符？

Answer 1

那个猪脚本不适合我 - 但改为：

A = LOAD '/path/to/file' USING PigStorage(',');
B = FOREACH A GENERATE $0 AS name, $1 as address, $2 as another;
C = FILTER B BY (name is NOT NULL);

确实有效。

Answer 2

嵌套的FOREACH将是更好的选择

B=FOREACH A {
   filtered_rec =  FILTER A BY (name is not null);
   GENERATE filtered_rec;
}