嗨这是http://pig.apache.org/docs/r0.10.0/test.html#describe的一个例子。
为什么A和B的架构包含一些“组”？我认为架构只有在你完成一个组命令之后才会有“组”（如在C中）。
A = LOAD 'student' AS (name:chararray, age:int, gpa:float);
B = FILTER A BY name matches 'J.+';
C = GROUP B BY name;
DESCRIBE A;
A: {group, B: (name: chararray,age: int,gpa: float}
DESCRIBE B;
B: {group, B: (name: chararray,age: int,gpa: float}
DESCRIBE C;
C: {group, chararry,B: (name: chararray,age: int,gpa: float}