Hadoop 如何使用PIG计算唯一用户数

下面的代码并不完全返回我试图计算的内容；唯一用户的数量。有什么想法吗

data = LOAD 'input_initial' AS (user_id,item_id,rating,timestamp);
data = FOREACH data GENERATE user_id,item_id;
STORE data INTO 'input_final';
data_users = FOREACH data GENERATE user_id;
group_users = GROUP data_users BY user_id;
count_users = FOREACH group_users GENERATE COUNT(data_users);
STORE count_users INTO 'count_users';

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您需要修改最终的组操作，以对“全部”而不是单个字段执行操作：

group_users = GROUP data_users BY user_id;
grp_all = GROUP group_users ALL;
count_users = FOREACH grp_all GENERATE COUNT(group_users);

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恐怕不行。您是否已测试并成功运行？