好 啊。如果你非常清楚r2中单个字段的值，那么你可以使用这个。
假设您知道r2文件中的值仅为100

A = load 'R1' as (a1, a2, a3, an);
B = load 'R2' as (b1);
C = foreach A generate a1,a2,a3,an,'100' as newalias;
DUMP C;

试试这个：

A = load 'R1' as (a1, a2, a3, an);
B = load 'R2' as (b1);
C = foreach A generate a1.., B.b1;
DUMP C;