I would like to filter the records after two files are joined.
The file BX-Books.csv contains the book data. and the file BX-Book-Ratings.csv contains books rating data where ISBN is the common column from both the files. The inner join betweeb the files is done using the this column.
I would like to get the books that are published in the year 2002.
I have used the following script but i am getting 0 records.
grunt> BookXRecords = LOAD '/user/pradeep/BX-Books.csv' USING PigStorage(';') AS (ISBN:chararray,BookTitle:chararray,BookAuthor:chararray,YearOfPublication:chararray, Publisher:chararray,ImageURLS:chararray,ImageURLM:chararray,ImageURLL:chararray);
grunt> BookXRating = LOAD '/user/pradeep/BX-Book-Ratings.csv' USING PigStorage(';') AS (user:chararray,ISBN:chararray,rating:chararray);
grunt> BxJoin = JOIN BookXRecords BY ISBN, BookXRating BY ISBN;
grunt> BxJoin_Mod = FOREACH BxJoin GENERATE $0 AS ISBN, $1, $2, $3, $4;
grunt> FLTRBx2002 = FILTER BxJoin_Mod BY $3 == '2002';
I created a test.csv and test-rating.csv and a Pig script that works out of them. It worked perfectly fine.
test.csv
1;abc;author1;2002
2;xyz;author2;2003
test-rating.csv
user1;1;3
user2;2;5
Pig Script :
A = LOAD 'test.csv' USING PigStorage(';') AS (ISBN:chararray,BookTitle:chararray,BookAuthor:chararray,YearOfPublication:chararray);
describe A;
dump A;
B = LOAD 'test-rating.csv' USING PigStorage(';') AS (user:chararray,ISBN:chararray,rating:chararray);
describe B;
dump B;
C = JOIN A BY ISBN, B BY ISBN;
describe C;
dump C;
D = FOREACH C GENERATE $0 as ISBN,$1,$2,$3;
describe D;
dump D;
E = FILTER D BY $3 == '2002';
describe E;
dump E;
Output:
A: {ISBN: chararray,BookTitle: chararray,BookAuthor: chararray,YearOfPublication: chararray}
(1,abc,author1,2002)
(2,xyz,author2,2003)
B: {user: chararray,ISBN: chararray,rating: chararray}
(user1,1,3)
(user2,2,5)
C: {A::ISBN: chararray,A::BookTitle: chararray,A::BookAuthor: chararray,A::YearOfPublication: chararray,B::user: chararray,B::ISBN: chararray,B::rating: chararray}
(1,abc,author1,2002,user1,1,3)
(2,xyz,author2,2003,user2,2,5)
D: {ISBN: chararray,A::BookTitle: chararray,A::BookAuthor: chararray,A::YearOfPublication: chararray}
(1,abc,author1,2002)
(2,xyz,author2,2003)
E: {ISBN: chararray,A::BookTitle: chararray,A::BookAuthor: chararray,A::YearOfPublication: chararray}
(1,abc,author1,2002)