limit - Piglatin 限制和展平会产生错误的结果

Question

B = GROUP A BY state;
C = FOREACH B {                          
   DA = ORDER A BY population DESC;                
   DB = LIMIT DA 5;                         
   GENERATE FLATTEN(group), FLATTEN(DB.name), FLATTEN(DB.population);
}

问题是我得到了 5 次而不是 1 次城市的名称。我得到如下信息：

(ALASKA,M,27257)
(ALASKA,M,23696)
(ALASKA,M,19949)
(ALASKA,M,19926)
(ALASKA,M,19833)
(ALASKA,H,27257)
(ALASKA,H,23696)
(ALASKA,H,19949)
(ALASKA,H,19926)
(ALASKA,H,19833)

我需要的输出是：

(ALASKA,M,27257)
(ALASKA,H,23696)

Answer 1

2个展平：展平（DB.name），展平（DB.population）；在 2 个袋子之间造成 Cartezian 产品，用一个替换它

B = GROUP A BY state;
C = FOREACH B {                          
   DA = ORDER A BY population DESC;                
   DB = LIMIT DA 5;                         
   GENERATE FLATTEN(group), FLATTEN(DB.(name, population));
}

或者当 GROUP BY 创建的包携带所有原始元组和所有列时，您可以这样做：

B = GROUP A BY state;
C = FOREACH B {                          
   DA = ORDER A BY population DESC;                
   DB = LIMIT DA 5;                         
   GENERATE FLATTEN(DB);
}