Maximum value of a column in apache pig

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Maximum value of a column in apache pig



I am trying to find the maximum value of a column ratingTime using pig.I am running below script :


ratings = LOAD '/user/maria_dev/ml-100k/u.data' AS (userid:int,movieID:int,rating:int, ratingTime:int);
maxrating = MAX(ratings.ratingTime);
DUMP maxrating



Sample Input data is :


196 242 3 881250949
186 302 3 891717742
22 377 1 878887116
244 51 2 880606923



I am getting below error :


2018-08-05 07:02:05,247 [main] INFO org.apache.pig.backend.hadoop.PigATSClient - Created ATS Hook

2018-08-05 07:02:05,914 [main] ERROR org.apache.pig.PigServer - exception during parsing: Error during parsing. <file script.pi





How are you running this? You're missing a semicolon on DUMP command
– cricket_007
Aug 5 at 13:28






I tried with semicolon as well, its still not working
– bp89
Aug 6 at 6:43





Again, how are you running this? pig -f or typing each line in the grunt shell? Can you please edit your post to include a sample of the input file?
– cricket_007
Aug 6 at 7:17



pig -f





I am running this pig script using ambari web console, also edited question to provide sample input.
– bp89
Aug 6 at 7:53





I think you need to load the file USING PigStorage
– cricket_007
Aug 6 at 12:06


USING PigStorage




1 Answer
1



You need a preceding GROUP ALL before applying MAX.Source


GROUP ALL


MAX


ratings = LOAD '/user/maria_dev/ml-100k/u.data' USING PigStorage('t') AS (userid:int,movieID:int,rating:int, ratingTime:int);
rating_group = GROUP ratings ALL;
maxrating = FOREACH ratings_group GENERATE MAX(ratings.ratingTime);
DUMP maxrating;





Thanks it worked for me!
– bp89
Aug 6 at 15:10






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