您可以为复杂数据类型提供模式，就像为基本数据类型提供模式一样：

grunt> data = LOAD 'file' USING PigStorage(';') AS (f1: chararray, f2: chararray);
grunt> t = FOREACH data GENERATE TOTUPLE(f1, f1) as t;
grunt> DESCRIBE t;
t: {t: (f1: chararray,f1: chararray)}
grunt> t = FOREACH t GENERATE t AS t:tuple(f3:chararray, f4:chararray);
grunt> DESCRIBE t;
t: {t: (f3: chararray,f4: chararray)}

如果你愿意，你可以省略 tuple 关键字：

grunt> t = FOREACH t GENERATE t AS t:(f5:chararray, f6:chararray);
grunt> DESCRIBE t;
t: {t: (f5: chararray,f6: chararray)}