好 啊。。可以使用秩运算符。
希望下面的代码有帮助。

rec = LOAD '/user/cloudera/inputfiles/sample.txt' USING PigStorage(',') AS(user:chararray,no:int,loc:chararray);
 rec_rank = rank rec;                                                                                     
 rec_rank_each = FOREACH rec_rank GENERATE $0 as rank_key, user, no, loc;                                 
 rec_rank_grp = GROUP rec_rank_each by user; 
 rec_rank_max = FOREACH rec_rank_grp GENERATE group as temp_user, MAX(rec_rank_each.rank_key) as max_rank;
 rec_join = JOIN rec_rank_each BY (user,rank_key) , rec_rank_min BY(temp_user,max_rank);
 rec_output = FOREACH rec_join GENERATE user,no,loc;
 dump rec_output;

确保您从pig0.11版本运行这个命令，作为从pig0.11引入的rank操作符

@阿尼尔：如果你按一个字段降序排列。你就能拿到最后一张唱片了。在下面的代码中，按输入的第二个字段排序（字段名：脚本中的no）
输入：

User1,7,LA 
User1,8,NYC 
User1,9,NYC 
User2,3,NYC
User2,4,DC

pig代码段：

user_details = LOAD 'user_details.csv'  USING  PigStorage(',') AS (user_name:chararray,no:long,city:chararray);

user_details_grp_user = GROUP user_details BY user_name;

required_user_details = FOREACH user_details_grp_user {
    user_details_sorted_by_no = ORDER user_details BY no DESC;
    top_record = LIMIT user_details_sorted_by_no 1;
    GENERATE FLATTEN(top_record);
}

输出：转储所需的用户详细信息

(User1,9,NYC )
(User2,4,DC)