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);
}

问题是我得到了城市的名字5次而不是1.我得到的结果是：

(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 flattens：FLATTEN（DB.name），FLATTEN（DB.population）;在2个袋子之间产生Cartezian产品，用一个袋子替换它

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，由GROUP BY创建的行李包含所有原始元组和所有列，您可以执行此操作：

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

染料限制和变平会产生错误的结果

1 个答案: