Hadoop Pig，如何在加入和分组后引用字段

我在Pig中有这段代码（win、request和response只是直接从文件系统加载的表）：

基本上，我想在加入和分组后对投标价格求和，但我得到一个错误：

Could not infer the matching function for org.apache.pig.builtin.SUM as multiple or none of them fit. Please use an explicit cast.

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我的猜测是，我没有正确地指的是

win.bid\u price

当执行多个联接时，我建议为您的字段使用唯一标识符（例如，bid\u id）。或者，您也可以使用“：：”，但这可能会变得非常脏

wins = LOAD '/user/hadoop/rtb/wins' USING PigStorage(',') AS (f1_w:int, f2_w:int,  f3_w:chararray);
reqs = LOAD '/user/hadoop/rtb/reqs' USING PigStorage(',') AS (f1_r:int, f2_r:int, f3_r:chararray);
resps = LOAD '/user/hadoop/rtb/resps' USING PigStorage(',') AS (f1_rp:int, f2_rp:int, f3_rp:chararray);

wins_reqs = JOIN wins BY f1_w, reqs BY f1_r;
wins_reqs_reps = JOIN wins_reqs BY f1_r, resps BY f1_rp;

win_group = GROUP wins_reqs_reps BY (f3_w);

win_sum = FOREACH win_group GENERATE group, SUM(wins_reqs_reps.f2_w);

wins = LOAD '/user/hadoop/rtb/wins' USING PigStorage(',') AS (f1_w:int, f2_w:int,  f3_w:chararray);
reqs = LOAD '/user/hadoop/rtb/reqs' USING PigStorage(',') AS (f1_r:int, f2_r:int, f3_r:chararray);
resps = LOAD '/user/hadoop/rtb/resps' USING PigStorage(',') AS (f1_rp:int, f2_rp:int, f3_rp:chararray);

wins_reqs = JOIN wins BY f1_w, reqs BY f1_r;
wins_reqs_reps = JOIN wins_reqs BY f1_r, resps BY f1_rp;

win_group = GROUP wins_reqs_reps BY (f3_w);

win_sum = FOREACH win_group GENERATE group, SUM(wins_reqs_reps.f2_w);