Having two tables: salary and employee，we can use Pig to find the most high-salary employees:

salary = LOAD '/user/robin/salaries/salaries.csv' USING PigStorage(',') AS (uid:int, salary:int, begin:chararray, end:chararray);
employee = LOAD '/user/robin/employees/employees.csv' USING PigStorage(',') AS (uid:int, birth:chararray, givenname:chararray, familyname:chararray, gender:chararray, work:chararray);
jo = JOIN employee BY uid, salary BY uid;
res = ORDER (
             FOREACH (
                      GROUP jo BY (employee::uid, employee::birth, employee::givenname, employee::familyname, employee::gender, employee::work)
             )
             GENERATE group.employee::uid, group.employee::givenname, group.employee::familyname, AVG(jo.salary::salary) AS avg_salary
      ) BY avg_salary DESC;
fs -rmr /user/sanbai/join_result;
STORE res INTO '/user/robin/join_result' USING PigStorage(',');

The result is:

109334,'Tsutomu','Alameldin',141835.33333333334
205000,'Charmane','Griswold',141064.63636363635
43624,'Tokuyasu','Pesch',138492.94444444444
493158,'Lidong','Meriste',138312.875
37558,'Juichirou','Thambidurai',138215.85714285713
276633,'Shin','Birdsall',136711.73333333334
238117,'Mitsuyuki','Stanfel',136026.2
46439,'Ibibia','Junet',135747.73333333334
254466,'Honesty','Mukaidono',135541.0625
253939,'Sanjai','Luders',135042.25
....