Hadoop - Pig

Ambari

• Ambari provides Dashboard:

  
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• Enable Admin Users:

ssh yourname@127.0.0.1 -p 2222
su root
ambari-admin-password-reset

Pig Concept

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• Usage of Pig:

1. Grunt
2. Script
3. Ambari

example -> find the oldest 5-star movie

• New Script in Pig View

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• Load data:

ratings = LOAD 'ml-100k/u.data' AS (userID:int, movieID:int, rating:int, ratingTime: int);

metadata = LOAD 'ml-100k/u.item' USING PigStorage('|') AS (movieID:int, movieTitle:chararray, releaseDate:chararray,
videoRelease:chararray, imdbLink:chararray);

• FOREACH/GENERATE:

nameLookup = FOREACH metadata GENERATE movieTitle, ToUnixTime(ToDate(releaseDate, 'dd-MM-yyyy')) AS releaseTime;

• Group By

ratingsByMovie = Group ratings BY movieID;

*Return Result:

avgRatings = Foreach ratingsByMovie Generate group AS movieID, AVG(ratings.rating) AS avgRating;
fiveStarMovies= Filter avgRatings By avgRating > 4.0;
fiveStarsWithData = join fiveStarMovies by movieID, nameLookup by movieID;
oldestFiveStarMovie = order fiveStarsWithData by nameLookup::releaseTime;

dump oldestFiveStarMovie;

• Result: (Runtime - several minutes)

  
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• With Tez, it can shrink into 1 minute

  
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