apache-pig - 如何将 1x1 别名转换为标量？

Question

我想将计数转化为概率:

total = foreach (group A all) generate SUM(A.count);
A = foreach A generate A.count / total as probability;

这不起作用，因为 total 是别名，而不是标量:

Invalid scalar projection: total : A column needs to be projected from a relation for it to be used as a scalar

Answer 1

即使别名 total 只有一个字段(总和)，您仍然必须引用该字段。

这应该有效:

total = foreach (group A all) generate SUM(A.count) as total;
A = foreach A generate A.count / total.total as probability;