pig:group by以后的其它统计方法一

 1 --测试Top N后的其它统计
 2 A = LOAD '/TraceParser/blackcore/' USING PigStorage() as (lk_id:chararray,host:chararray);
 3 --DUMP A;
 4 
 5 B = GROUP A BY lk_id;
 6 B = FOREACH B GENERATE group as lk_id,COUNT($1) as amount;
 7 --DUMP B;
 8 
 9 --TOP N的数据集
10 C = ORDER B BY amount DESC;
11 C = LIMIT C 5;
12 --DUMP C;
13 
14 --除TOP N后的数据集归并为其它
15 D = JOIN B BY lk_id LEFT OUTER,C BY lk_id;
16 --DESCRIBE D;
17 --DUMP D;
18 E = FILTER D BY C::lk_id is null OR C::lk_id == '';
19 --DUMP E;
20 E = FOREACH E GENERATE B::lk_id,B::amount;
21 --DESCRIBE E;
22 --SUM的用法？
23 
24 --DUMP E;
25 --DUMP A;
26 H = JOIN E BY B::lk_id,A BY lk_id;
27 DESCRIBE H;
28 --H: {E::B::lk_id: chararray,E::B::amount: long,A::lk_id: chararray,A::host: chararray}
29 --DUMP H;
30 I = GROUP H all;
31 I = FOREACH I GENERATE '其它',COUNT($1) as amount;
32 DUMP I;