intro_to_mapreduce

intro_to_mapreduce - • Shuffling • Merging • Reduce...

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CPS216: Advanced Database Systems (Data-intensive Computing Systems) Introduction to MapReduce and Hadoop Shivnath Babu
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Word Count over a Given Set of Web Pages see bob throw see 1 bob 1 throw 1 see 1 spot 1 run 1 bob 1 run 1 see 2 spot 1 throw 1 see spot run Can we do word count in parallel?
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The MapReduce Framework (pioneered by Google)
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Automatic Parallel Execution in MapReduce (Google) Handles failures automatically, e.g., restarts tasks if a node fails; runs multiples copies of the same task to avoid a slow task slowing down the whole job
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MapReduce in Hadoop (1)
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MapReduce in Hadoop (2)
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MapReduce in Hadoop (3)
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Data Flow in a MapReduce Program in Hadoop InputFormat Map function Partitioner Sorting & Merging Combiner
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Unformatted text preview: • Shuffling • Merging • Reduce function • OutputFormat 1:many Lifecycle of a MapReduce Job Map function Reduce function Run this program as a MapReduce job Lifecycle of a MapReduce Job Map function Reduce function Run this program as a MapReduce job Map Wave 1 Reduce Wave 1 Map Wave 2 Reduce Wave 2 Input Splits Lifecycle of a MapReduce Job Time How are the number of splits, number of map and reduce tasks, memory allocation to tasks, etc., determined? Job Configuration Parameters • 190+ parameters in Hadoop • Set manually or defaults are used How to sort data using Hadoop? Let us look at a complete example MapReduce program in Hadoop...
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