如何在pig latin脚本中生成null

Question

  

我尝试使用以下代码 -

a = load 'some_loc';
b = foreach a generate '' as first,
null as second,
NULL as third,
'null' as forth;

  

你能告诉我哪一个是正确的还是我必须添加   用于生成null的脚本中的其他内容。

Answer 1

null是保留关键字且不区分大小写，您可以自由使用null或NULL。

A = LOAD 'data' AS (a, b, c).
B = FOREACH A GENERATE a, null;

请参考 Nulls and Pig Latin

Answer 2

以下应该没问题

null as second,
NULL as third,