我在Pig中有这个代码(win,request和response只是直接从文件系统加载的表):
win_request = JOIN win BY bid_id, request BY bid_id;
win_request_response = JOIN win_request BY win.bid_id, response BY bid_id;
win_group = GROUP win_request_response BY (win.campaign_id);
win_count = FOREACH win_group GENERATE group, SUM(win.bid_price);
基本上我想在加入和分组后总结bid_price,但是我收到错误:
Could not infer the matching function for org.apache.pig.builtin.SUM as multiple or none of them fit. Please use an explicit cast.
我的猜测是我没有正确引用win.bid_price
。
答案 0 :(得分:7)
执行多个联接时,我建议您为字段使用唯一标识符(例如,对于bid_id)。或者,您也可以使用disambiguation operator'::',但这可能会非常脏。
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);