Mapreduce examples starting from the basic WordCount to a more complex K-means algorithm. The code contained in these slides is available at https://github.com/andreaiacono/MapReduce
A MapReduce job usually splits the input data-set into independent chunks which are processed by the map tasks in a completely parallel manner. The framework sorts the outputs of the maps, which are then input to the reduce tasks. Typically both the input and the output of the job are stored in a file-system.
This document discusses Hadoop, an open-source software framework for distributed storage and processing of large datasets across clusters of computers. It describes how Hadoop uses HDFS for distributed storage and fault tolerance, YARN for resource management, and MapReduce for parallel processing of large datasets. It provides details on the architecture of HDFS including the name node, data nodes, and clients. It also explains the MapReduce programming model and job execution involving map and reduce tasks. Finally, it states that as data volumes continue rising, Hadoop provides an affordable solution for large-scale data handling and analysis through its distributed and scalable architecture.
This document provides an introduction to Apache Hadoop, which is an open-source software framework for distributed storage and processing of large datasets. It discusses Hadoop's main components of MapReduce and HDFS. MapReduce is a programming model for processing large datasets in a distributed manner, while HDFS provides distributed, fault-tolerant storage. Hadoop runs on commodity computer clusters and can scale to thousands of nodes.
This presentation discusses the follow topics
What is Hadoop?
Need for Hadoop
History of Hadoop
Hadoop Overview
Advantages and Disadvantages of Hadoop
Hadoop Distributed File System
Comparing: RDBMS vs. Hadoop
Advantages and Disadvantages of HDFS
Hadoop frameworks
Modules of Hadoop frameworks
Features of 'Hadoop‘
Hadoop Analytics Tools
MapReduce is a programming model for processing large datasets in a distributed system. It involves a map step that performs filtering and sorting, and a reduce step that performs summary operations. Hadoop is an open-source framework that supports MapReduce. It orchestrates tasks across distributed servers, manages communications and fault tolerance. Main steps include mapping of input data, shuffling of data between nodes, and reducing of shuffled data.
Apache Sqoop efficiently transfers bulk data between Apache Hadoop and structured datastores such as relational databases. Sqoop helps offload certain tasks (such as ETL processing) from the EDW to Hadoop for efficient execution at a much lower cost. Sqoop can also be used to extract data from Hadoop and export it into external structured datastores. Sqoop works with relational databases such as Teradata, Netezza, Oracle, MySQL, Postgres, and HSQLDB
Big Data raises challenges about how to process such vast pool of raw data and how to aggregate value to our lives. For addressing these demands an ecosystem of tools named Hadoop was conceived.
This document provides an overview of the Hadoop MapReduce Fundamentals course. It discusses what Hadoop is, why it is used, common business problems it can address, and companies that use Hadoop. It also outlines the core parts of Hadoop distributions and the Hadoop ecosystem. Additionally, it covers common MapReduce concepts like HDFS, the MapReduce programming model, and Hadoop distributions. The document includes several code examples and screenshots related to Hadoop and MapReduce.
Hive Tutorial | Hive Architecture | Hive Tutorial For Beginners | Hive In Had...
This presentation about Hive will help you understand the history of Hive, what is Hive, Hive architecture, data flow in Hive, Hive data modeling, Hive data types, different modes in which Hive can run on, differences between Hive and RDBMS, features of Hive and a demo on HiveQL commands. Hive is a data warehouse system which is used for querying and analyzing large datasets stored in HDFS. Hive uses a query language called HiveQL which is similar to SQL. Hive issues SQL abstraction to integrate SQL queries (like HiveQL) into Java without the necessity to implement queries in the low-level Java API. Now, let us get started and understand Hadoop Hive in detail
Below topics are explained in this Hive presetntation:
1. History of Hive
2. What is Hive?
3. Architecture of Hive
4. Data flow in Hive
5. Hive data modeling
6. Hive data types
7. Different modes of Hive
8. Difference between Hive and RDBMS
9. Features of Hive
10. Demo on HiveQL
What is this Big Data Hadoop training course about?
The Big Data Hadoop and Spark developer course have been designed to impart in-depth knowledge of Big Data processing using Hadoop and Spark. The course is packed with real-life projects and case studies to be executed in the CloudLab.
What are the course objectives?
This course will enable you to:
1. Understand the different components of the Hadoop ecosystem such as Hadoop 2.7, Yarn, MapReduce, Pig, Hive, Impala, HBase, Sqoop, Flume, and Apache Spark
2. Understand Hadoop Distributed File System (HDFS) and YARN as well as their architecture, and learn how to work with them for storage and resource management
3. Understand MapReduce and its characteristics, and assimilate some advanced MapReduce concepts
4. Get an overview of Sqoop and Flume and describe how to ingest data using them
5. Create database and tables in Hive and Impala, understand HBase, and use Hive and Impala for partitioning
6. Understand different types of file formats, Avro Schema, using Arvo with Hive, and Sqoop and Schema evolution
7. Understand Flume, Flume architecture, sources, flume sinks, channels, and flume configurations
8. Understand HBase, its architecture, data storage, and working with HBase. You will also understand the difference between HBase and RDBMS
9. Gain a working knowledge of Pig and its components
10. Do functional programming in Spark
11. Understand resilient distribution datasets (RDD) in detail
12. Implement and build Spark applications
13. Gain an in-depth understanding of parallel processing in Spark and Spark RDD optimization techniques
14. Understand the common use-cases of Spark and the various interactive algorithms
15. Learn Spark SQL, creating, transforming, and querying Data frames
Learn more at https://www.simplilearn.com/big-data-and-analytics/big-data-and-hadoop-training
Apache Spark is a In Memory Data Processing Solution that can work with existing data source like HDFS and can make use of your existing computation infrastructure like YARN/Mesos etc. This talk will cover a basic introduction of Apache Spark with its various components like MLib, Shark, GrpahX and with few examples.
Storm is a distributed and fault-tolerant realtime computation system. It was created at BackType/Twitter to analyze tweets, links, and users on Twitter in realtime. Storm provides scalability, reliability, and ease of programming. It uses components like Zookeeper, ØMQ, and Thrift. A Storm topology defines the flow of data between spouts that read data and bolts that process data. Storm guarantees processing of all data through its reliability APIs and guarantees no data loss even during failures.
Apache Hive is a data warehouse software built on top of Hadoop that allows users to query data stored in various databases and file systems using an SQL-like interface. It provides a way to summarize, query, and analyze large datasets stored in Hadoop distributed file system (HDFS). Hive gives SQL capabilities to analyze data without needing MapReduce programming. Users can build a data warehouse by creating Hive tables, loading data files into HDFS, and then querying and analyzing the data using HiveQL, which Hive then converts into MapReduce jobs.
Hadoop Tutorial For Beginners | Apache Hadoop Tutorial For Beginners | Hadoop...
This presentation about Hadoop for beginners will help you understand what is Hadoop, why Hadoop, what is Hadoop HDFS, Hadoop MapReduce, Hadoop YARN, a use case of Hadoop and finally a demo on HDFS (Hadoop Distributed File System), MapReduce and YARN. Big Data is a massive amount of data which cannot be stored, processed, and analyzed using traditional systems. To overcome this problem, we use Hadoop. Hadoop is a framework which stores and handles Big Data in a distributed and parallel fashion. Hadoop overcomes the challenges of Big Data. Hadoop has three components HDFS, MapReduce, and YARN. HDFS is the storage unit of Hadoop, MapReduce is its processing unit, and YARN is the resource management unit of Hadoop. In this video, we will look into these units individually and also see a demo on each of these units.
Below topics are explained in this Hadoop presentation:
1. What is Hadoop
2. Why Hadoop
3. Big Data generation
4. Hadoop HDFS
5. Hadoop MapReduce
6. Hadoop YARN
7. Use of Hadoop
8. Demo on HDFS, MapReduce and YARN
What is this Big Data Hadoop training course about?
The Big Data Hadoop and Spark developer course have been designed to impart an in-depth knowledge of Big Data processing using Hadoop and Spark. The course is packed with real-life projects and case studies to be executed in the CloudLab.
What are the course objectives?
This course will enable you to:
1. Understand the different components of the Hadoop ecosystem such as Hadoop 2.7, Yarn, MapReduce, Pig, Hive, Impala, HBase, Sqoop, Flume, and Apache Spark
2. Understand Hadoop Distributed File System (HDFS) and YARN as well as their architecture, and learn how to work with them for storage and resource management
3. Understand MapReduce and its characteristics, and assimilate some advanced MapReduce concepts
4. Get an overview of Sqoop and Flume and describe how to ingest data using them
5. Create database and tables in Hive and Impala, understand HBase, and use Hive and Impala for partitioning
6. Understand different types of file formats, Avro Schema, using Arvo with Hive, and Sqoop and Schema evolution
7. Understand Flume, Flume architecture, sources, flume sinks, channels, and flume configurations
8. Understand HBase, its architecture, data storage, and working with HBase. You will also understand the difference between HBase and RDBMS
9. Gain a working knowledge of Pig and its components
10. Do functional programming in Spark
11. Understand resilient distribution datasets (RDD) in detail
12. Implement and build Spark applications
13. Gain an in-depth understanding of parallel processing in Spark and Spark RDD optimization techniques
14. Understand the common use-cases of Spark and the various interactive algorithms
15. Learn Spark SQL, creating, transforming, and querying Data frames
Learn more at https://www.simplilearn.com/big-data-and-analytics/big-data-and-hadoop-training
This Hadoop tutorial on MapReduce Example ( Mapreduce Tutorial Blog Series: https://goo.gl/w0on2G ) will help you understand how to write a MapReduce program in Java. You will also get to see multiple mapreduce examples on Analytics and Testing.
Check our complete Hadoop playlist here: https://goo.gl/ExJdZs
Below are the topics covered in this tutorial:
1) MapReduce Way
2) Classes and Packages in MapReduce
3) Explanation of a Complete MapReduce Program
4) MapReduce Examples on Analytics
5) MapReduce Example on Testing - MRUnit
The presentation covers following topics: 1) Hadoop Introduction 2) Hadoop nodes and daemons 3) Architecture 4) Hadoop best features 5) Hadoop characteristics. For more further knowledge of Hadoop refer the link: http://data-flair.training/blogs/hadoop-tutorial-for-beginners/
Redis is an in-memory key-value store that is often used as a database, cache, and message broker. It supports various data structures like strings, hashes, lists, sets, and sorted sets. While data is stored in memory for fast access, Redis can also persist data to disk. It is widely used by companies like GitHub, Craigslist, and Engine Yard to power applications with high performance needs.
Hadoop became the most common systm to store big data.
With Hadoop, many supporting systems emerged to complete the aspects that are missing in Hadoop itself.
Together they form a big ecosystem.
This presentation covers some of those systems.
While not capable to cover too many in one presentation, I tried to focus on the most famous/popular ones and on the most interesting ones.
This document provides an overview of key concepts in Hadoop including:
- Hadoop was tested on a 4000 node cluster with 32,000 cores and 16 petabytes of storage.
- MapReduce is Hadoop's programming model and consists of mappers that process input splits in parallel, and reducers that combine the outputs of the mappers.
- The JobTracker manages jobs, TaskTrackers run tasks on slave nodes, and Tasks are individual mappers or reducers. Data is distributed to nodes implicitly based on the HDFS file distribution. Configurations are set using a JobConf object.
Hadoop became the most common systm to store big data.
With Hadoop, many supporting systems emerged to complete the aspects that are missing in Hadoop itself.
Together they form a big ecosystem.
This presentation covers some of those systems.
While not capable to cover too many in one presentation, I tried to focus on the most famous/popular ones and on the most interesting ones.
This document provides a technical introduction to Hadoop, including:
- Hadoop has been tested on a 4000 node cluster with 32,000 cores and 16 petabytes of storage.
- Key Hadoop concepts are explained, including jobs, tasks, task attempts, mappers, reducers, and the JobTracker and TaskTracker processes.
- The flow of a MapReduce job is described, from the client submitting the job to the JobTracker, TaskTrackers running tasks on data splits using the mapper and reducer classes, and writing outputs.
This document provides a technical introduction to Hadoop, including:
- Hadoop has been tested on a 4000 node cluster with 32,000 cores and 16 petabytes of storage.
- Key Hadoop concepts are explained, including jobs, tasks, task attempts, mappers, reducers, and the JobTracker and TaskTrackers.
- The process of launching a MapReduce job is described, from the client submitting the job to the JobTracker distributing tasks to TaskTrackers and running the user-defined mapper and reducer classes.
Hadoop is an open source framework for distributed storage and processing of vast amounts of data across clusters of computers. It uses a master-slave architecture with a single JobTracker master and multiple TaskTracker slaves. The JobTracker schedules tasks like map and reduce jobs on TaskTrackers, which each run task instances in separate JVMs. It monitors task progress and reschedules failed tasks. Hadoop uses MapReduce programming model where the input is split and mapped in parallel, then outputs are shuffled, sorted, and reduced to form the final results.
The document provides interview questions and answers related to Hadoop. It discusses common InputFormats in Hadoop like TextInputFormat, KeyValueInputFormat, and SequenceFileInputFormat. It also describes concepts like InputSplit, RecordReader, partitioner, combiner, job tracker, task tracker, jobs and tasks relationship, debugging Hadoop code, and handling lopsided jobs. HDFS, its architecture, replication, and reading files from HDFS is also covered.
Hadoop is an open-source software framework for distributed storage and processing of large datasets across clusters of computers. It provides reliable storage through HDFS and distributed processing via MapReduce. HDFS handles storage and MapReduce provides a programming model for parallel processing of large datasets across a cluster. The MapReduce framework consists of a mapper that processes input key-value pairs in parallel, and a reducer that aggregates the output of the mappers by key.
This document provides an overview of applied recommender systems. It discusses Hadoop, MapReduce, Hive, Mahout and collaborative filtering recommender algorithms. Hadoop is used to process large datasets in parallel across clusters. MapReduce is the programming model and Hive provides a SQL-like interface. Mahout contains machine learning libraries including collaborative filtering algorithms to generate recommendations. Pearson correlation is discussed as an item-item collaborative filtering approach.
Vibrant Technologies is headquarted in Mumbai,India.We are the best Hadoop training provider in Navi Mumbai who provides Live Projects to students.We provide Corporate Training also.We are Best Hadoop classes in Mumbai according to our students and corporates
The document contains 31 questions and answers related to Hadoop concepts. It covers topics like common input formats in Hadoop, differences between TextInputFormat and KeyValueInputFormat, what are InputSplits and how they are created, how partitioning, shuffling and sorting occurs after the map phase, what is a combiner, functions of JobTracker and TaskTracker, how speculative execution works, using distributed cache and counters, setting number of mappers/reducers, writing custom partitioners, debugging Hadoop jobs, and failure handling processes for production Hadoop jobs.
This document provides an introduction to MapReduce and Hadoop, including an overview of computing PageRank using MapReduce. It discusses how MapReduce addresses challenges of parallel programming by hiding details of distributed systems. It also demonstrates computing PageRank on Hadoop through parallel matrix multiplication and implementing custom file formats.
Hadoop interview questions for freshers and experienced people. This is the best place for all beginners and Experts who are eager to learn Hadoop Tutorial from the scratch.
Read more here http://softwarequery.com/hadoop/
The document discusses key concepts related to Hadoop including its components like HDFS, MapReduce, Pig, Hive, and HBase. It provides explanations of HDFS architecture and functions, how MapReduce works through map and reduce phases, and how higher-level tools like Pig and Hive allow for more simplified programming compared to raw MapReduce. The summary also mentions that HBase is a NoSQL database that provides fast random access to large datasets on Hadoop, while HCatalog provides a relational abstraction layer for HDFS data.
Hadoop and Pig are tools for analyzing large datasets. Hadoop uses MapReduce and HDFS for distributed processing and storage. Pig provides a high-level language for expressing data analysis jobs that are compiled into MapReduce programs. Common tasks like joins, filters, and grouping are built into Pig for easier programming compared to lower-level MapReduce.
Apache Spark is written in Scala programming language that compiles the program code into byte code for the JVM for spark big data processing.
The open source community has developed a wonderful utility for spark python big data processing known as PySpark.
Stratosphere System Overview Big Data Beers Berlin. 20.11.2013
Stratosphere is the next generation big data processing engine.
These slides introduce the most important features of Stratosphere by comparing it with Apache Hadoop.
For more information, visit stratosphere.eu
Based on university research, it is now a completely open-source, community driven development with focus on stability and usability.
Getting started with Hadoop, Hive, and Elastic MapReduce
1) The document provides an overview of tools for distributed computing including MapReduce, Hadoop, Hive, and Elastic MapReduce.
2) It discusses getting started with Elastic MapReduce using Python with mrjob or the AWS command line and challenges with getting started with Hive.
3) Potential pitfalls with EMR are also outlined such as JVM memory issues and problems with multiple small output files.
Writing MapReduce Programs using Java | Big Data Hadoop Spark Tutorial | Clou...
Big Data with Hadoop & Spark Training: http://bit.ly/2kyXPo0
This CloudxLab Writing MapReduce Programs tutorial helps you to understand how to write MapReduce Programs using Java in detail. Below are the topics covered in this tutorial:
1) Why MapReduce?
2) Write a MapReduce Job to Count Unique Words in a Text File
3) Create Mapper and Reducer in Java
4) Create Driver
5) MapReduce Input Splits, Secondary Sorting, and Partitioner
6) Combiner Functions in MapReduce
7) Job Chaining and Pipes in MapReduce
Processing massive amount of data with Map Reduce using Apache Hadoop - Indi...
This document provides an overview of MapReduce and Hadoop. It describes the Map and Reduce functions, explaining that Map applies a function to each element of a list and Reduce reduces a list to a single value. It gives examples of Map and Reduce using employee salary data. It then discusses Hadoop and its core components HDFS for distributed storage and MapReduce for distributed processing. Key aspects covered include the NameNode, DataNodes, input/output formats, and the job launch process. It also addresses some common questions around small files, large files, and accessing SQL data from Hadoop.
GraphX is Apache Spark's API for graph distributed computing based on the Pregel programming model. In this talk we'll see a brief introduction to Pregel and then we'll focus on transforming standard graph algorithms in their distributed counterpart using GraphX to speedup performance in a distributed environment.
Graphs are everywhere! Distributed graph computing with Spark GraphX
This document discusses GraphX, a graph processing system built on Apache Spark. It defines what graphs are, including vertices and edges. It explains that GraphX uses Resilient Distributed Datasets (RDDs) to keep data in memory for iterative graph algorithms. GraphX implements the Pregel computational model where each vertex can modify its state, receive and send messages to neighbors each superstep until halting. The document provides examples of graph algorithms and notes when GraphX is well-suited versus a graph database.
The document summarizes Spark SQL, which is a Spark module for structured data processing. It introduces key concepts like RDDs, DataFrames, and interacting with data sources. The architecture of Spark SQL is explained, including how it works with different languages and data sources through its schema RDD abstraction. Features of Spark SQL are covered such as its integration with Spark programs, unified data access, compatibility with Hive, and standard connectivity.
Hadoop is a distributed processing framework for large datasets. It utilizes HDFS for storage and MapReduce as its programming model. The Hadoop ecosystem has expanded to include many other tools. YARN was developed to address limitations in the original Hadoop architecture. It provides a common platform for various data processing engines like MapReduce, Spark, and Storm. YARN improves scalability, utilization, and supports multiple workloads by decoupling cluster resource management from application logic. It allows different applications to leverage shared Hadoop cluster resources.
Here is how you can solve this problem using MapReduce and Unix commands:
Map step:
grep -o 'Blue\|Green' input.txt | wc -l > output
This uses grep to search the input file for the strings "Blue" or "Green" and print only the matches. The matches are piped to wc which counts the lines (matches).
Reduce step:
cat output
This isn't really needed as there is only one mapper. Cat prints the contents of the output file which has the count of Blue and Green.
So MapReduce has been simulated using grep for the map and cat for the reduce functionality. The key aspects are - grep extracts the relevant data (map
A MapReduce job usually splits the input data-set into independent chunks which are processed by the map tasks in a completely parallel manner. The framework sorts the outputs of the maps, which are then input to the reduce tasks. Typically both the input and the output of the job are stored in a file-system.
This document discusses Hadoop, an open-source software framework for distributed storage and processing of large datasets across clusters of computers. It describes how Hadoop uses HDFS for distributed storage and fault tolerance, YARN for resource management, and MapReduce for parallel processing of large datasets. It provides details on the architecture of HDFS including the name node, data nodes, and clients. It also explains the MapReduce programming model and job execution involving map and reduce tasks. Finally, it states that as data volumes continue rising, Hadoop provides an affordable solution for large-scale data handling and analysis through its distributed and scalable architecture.
Introduction to Hadoop and Hadoop component rebeccatho
This document provides an introduction to Apache Hadoop, which is an open-source software framework for distributed storage and processing of large datasets. It discusses Hadoop's main components of MapReduce and HDFS. MapReduce is a programming model for processing large datasets in a distributed manner, while HDFS provides distributed, fault-tolerant storage. Hadoop runs on commodity computer clusters and can scale to thousands of nodes.
This presentation discusses the follow topics
What is Hadoop?
Need for Hadoop
History of Hadoop
Hadoop Overview
Advantages and Disadvantages of Hadoop
Hadoop Distributed File System
Comparing: RDBMS vs. Hadoop
Advantages and Disadvantages of HDFS
Hadoop frameworks
Modules of Hadoop frameworks
Features of 'Hadoop‘
Hadoop Analytics Tools
MapReduce is a programming model for processing large datasets in a distributed system. It involves a map step that performs filtering and sorting, and a reduce step that performs summary operations. Hadoop is an open-source framework that supports MapReduce. It orchestrates tasks across distributed servers, manages communications and fault tolerance. Main steps include mapping of input data, shuffling of data between nodes, and reducing of shuffled data.
Apache Sqoop efficiently transfers bulk data between Apache Hadoop and structured datastores such as relational databases. Sqoop helps offload certain tasks (such as ETL processing) from the EDW to Hadoop for efficient execution at a much lower cost. Sqoop can also be used to extract data from Hadoop and export it into external structured datastores. Sqoop works with relational databases such as Teradata, Netezza, Oracle, MySQL, Postgres, and HSQLDB
Big Data raises challenges about how to process such vast pool of raw data and how to aggregate value to our lives. For addressing these demands an ecosystem of tools named Hadoop was conceived.
This document provides an overview of the Hadoop MapReduce Fundamentals course. It discusses what Hadoop is, why it is used, common business problems it can address, and companies that use Hadoop. It also outlines the core parts of Hadoop distributions and the Hadoop ecosystem. Additionally, it covers common MapReduce concepts like HDFS, the MapReduce programming model, and Hadoop distributions. The document includes several code examples and screenshots related to Hadoop and MapReduce.
Hive Tutorial | Hive Architecture | Hive Tutorial For Beginners | Hive In Had...Simplilearn
This presentation about Hive will help you understand the history of Hive, what is Hive, Hive architecture, data flow in Hive, Hive data modeling, Hive data types, different modes in which Hive can run on, differences between Hive and RDBMS, features of Hive and a demo on HiveQL commands. Hive is a data warehouse system which is used for querying and analyzing large datasets stored in HDFS. Hive uses a query language called HiveQL which is similar to SQL. Hive issues SQL abstraction to integrate SQL queries (like HiveQL) into Java without the necessity to implement queries in the low-level Java API. Now, let us get started and understand Hadoop Hive in detail
Below topics are explained in this Hive presetntation:
1. History of Hive
2. What is Hive?
3. Architecture of Hive
4. Data flow in Hive
5. Hive data modeling
6. Hive data types
7. Different modes of Hive
8. Difference between Hive and RDBMS
9. Features of Hive
10. Demo on HiveQL
What is this Big Data Hadoop training course about?
The Big Data Hadoop and Spark developer course have been designed to impart in-depth knowledge of Big Data processing using Hadoop and Spark. The course is packed with real-life projects and case studies to be executed in the CloudLab.
What are the course objectives?
This course will enable you to:
1. Understand the different components of the Hadoop ecosystem such as Hadoop 2.7, Yarn, MapReduce, Pig, Hive, Impala, HBase, Sqoop, Flume, and Apache Spark
2. Understand Hadoop Distributed File System (HDFS) and YARN as well as their architecture, and learn how to work with them for storage and resource management
3. Understand MapReduce and its characteristics, and assimilate some advanced MapReduce concepts
4. Get an overview of Sqoop and Flume and describe how to ingest data using them
5. Create database and tables in Hive and Impala, understand HBase, and use Hive and Impala for partitioning
6. Understand different types of file formats, Avro Schema, using Arvo with Hive, and Sqoop and Schema evolution
7. Understand Flume, Flume architecture, sources, flume sinks, channels, and flume configurations
8. Understand HBase, its architecture, data storage, and working with HBase. You will also understand the difference between HBase and RDBMS
9. Gain a working knowledge of Pig and its components
10. Do functional programming in Spark
11. Understand resilient distribution datasets (RDD) in detail
12. Implement and build Spark applications
13. Gain an in-depth understanding of parallel processing in Spark and Spark RDD optimization techniques
14. Understand the common use-cases of Spark and the various interactive algorithms
15. Learn Spark SQL, creating, transforming, and querying Data frames
Learn more at https://www.simplilearn.com/big-data-and-analytics/big-data-and-hadoop-training
Apache Spark is a In Memory Data Processing Solution that can work with existing data source like HDFS and can make use of your existing computation infrastructure like YARN/Mesos etc. This talk will cover a basic introduction of Apache Spark with its various components like MLib, Shark, GrpahX and with few examples.
Storm is a distributed and fault-tolerant realtime computation system. It was created at BackType/Twitter to analyze tweets, links, and users on Twitter in realtime. Storm provides scalability, reliability, and ease of programming. It uses components like Zookeeper, ØMQ, and Thrift. A Storm topology defines the flow of data between spouts that read data and bolts that process data. Storm guarantees processing of all data through its reliability APIs and guarantees no data loss even during failures.
Apache Hive is a data warehouse software built on top of Hadoop that allows users to query data stored in various databases and file systems using an SQL-like interface. It provides a way to summarize, query, and analyze large datasets stored in Hadoop distributed file system (HDFS). Hive gives SQL capabilities to analyze data without needing MapReduce programming. Users can build a data warehouse by creating Hive tables, loading data files into HDFS, and then querying and analyzing the data using HiveQL, which Hive then converts into MapReduce jobs.
Hadoop Tutorial For Beginners | Apache Hadoop Tutorial For Beginners | Hadoop...Simplilearn
This presentation about Hadoop for beginners will help you understand what is Hadoop, why Hadoop, what is Hadoop HDFS, Hadoop MapReduce, Hadoop YARN, a use case of Hadoop and finally a demo on HDFS (Hadoop Distributed File System), MapReduce and YARN. Big Data is a massive amount of data which cannot be stored, processed, and analyzed using traditional systems. To overcome this problem, we use Hadoop. Hadoop is a framework which stores and handles Big Data in a distributed and parallel fashion. Hadoop overcomes the challenges of Big Data. Hadoop has three components HDFS, MapReduce, and YARN. HDFS is the storage unit of Hadoop, MapReduce is its processing unit, and YARN is the resource management unit of Hadoop. In this video, we will look into these units individually and also see a demo on each of these units.
Below topics are explained in this Hadoop presentation:
1. What is Hadoop
2. Why Hadoop
3. Big Data generation
4. Hadoop HDFS
5. Hadoop MapReduce
6. Hadoop YARN
7. Use of Hadoop
8. Demo on HDFS, MapReduce and YARN
What is this Big Data Hadoop training course about?
The Big Data Hadoop and Spark developer course have been designed to impart an in-depth knowledge of Big Data processing using Hadoop and Spark. The course is packed with real-life projects and case studies to be executed in the CloudLab.
What are the course objectives?
This course will enable you to:
1. Understand the different components of the Hadoop ecosystem such as Hadoop 2.7, Yarn, MapReduce, Pig, Hive, Impala, HBase, Sqoop, Flume, and Apache Spark
2. Understand Hadoop Distributed File System (HDFS) and YARN as well as their architecture, and learn how to work with them for storage and resource management
3. Understand MapReduce and its characteristics, and assimilate some advanced MapReduce concepts
4. Get an overview of Sqoop and Flume and describe how to ingest data using them
5. Create database and tables in Hive and Impala, understand HBase, and use Hive and Impala for partitioning
6. Understand different types of file formats, Avro Schema, using Arvo with Hive, and Sqoop and Schema evolution
7. Understand Flume, Flume architecture, sources, flume sinks, channels, and flume configurations
8. Understand HBase, its architecture, data storage, and working with HBase. You will also understand the difference between HBase and RDBMS
9. Gain a working knowledge of Pig and its components
10. Do functional programming in Spark
11. Understand resilient distribution datasets (RDD) in detail
12. Implement and build Spark applications
13. Gain an in-depth understanding of parallel processing in Spark and Spark RDD optimization techniques
14. Understand the common use-cases of Spark and the various interactive algorithms
15. Learn Spark SQL, creating, transforming, and querying Data frames
Learn more at https://www.simplilearn.com/big-data-and-analytics/big-data-and-hadoop-training
This Hadoop tutorial on MapReduce Example ( Mapreduce Tutorial Blog Series: https://goo.gl/w0on2G ) will help you understand how to write a MapReduce program in Java. You will also get to see multiple mapreduce examples on Analytics and Testing.
Check our complete Hadoop playlist here: https://goo.gl/ExJdZs
Below are the topics covered in this tutorial:
1) MapReduce Way
2) Classes and Packages in MapReduce
3) Explanation of a Complete MapReduce Program
4) MapReduce Examples on Analytics
5) MapReduce Example on Testing - MRUnit
The presentation covers following topics: 1) Hadoop Introduction 2) Hadoop nodes and daemons 3) Architecture 4) Hadoop best features 5) Hadoop characteristics. For more further knowledge of Hadoop refer the link: http://data-flair.training/blogs/hadoop-tutorial-for-beginners/
Redis is an in-memory key-value store that is often used as a database, cache, and message broker. It supports various data structures like strings, hashes, lists, sets, and sorted sets. While data is stored in memory for fast access, Redis can also persist data to disk. It is widely used by companies like GitHub, Craigslist, and Engine Yard to power applications with high performance needs.
Hadoop became the most common systm to store big data.
With Hadoop, many supporting systems emerged to complete the aspects that are missing in Hadoop itself.
Together they form a big ecosystem.
This presentation covers some of those systems.
While not capable to cover too many in one presentation, I tried to focus on the most famous/popular ones and on the most interesting ones.
This document provides an overview of key concepts in Hadoop including:
- Hadoop was tested on a 4000 node cluster with 32,000 cores and 16 petabytes of storage.
- MapReduce is Hadoop's programming model and consists of mappers that process input splits in parallel, and reducers that combine the outputs of the mappers.
- The JobTracker manages jobs, TaskTrackers run tasks on slave nodes, and Tasks are individual mappers or reducers. Data is distributed to nodes implicitly based on the HDFS file distribution. Configurations are set using a JobConf object.
Hadoop became the most common systm to store big data.
With Hadoop, many supporting systems emerged to complete the aspects that are missing in Hadoop itself.
Together they form a big ecosystem.
This presentation covers some of those systems.
While not capable to cover too many in one presentation, I tried to focus on the most famous/popular ones and on the most interesting ones.
This document provides a technical introduction to Hadoop, including:
- Hadoop has been tested on a 4000 node cluster with 32,000 cores and 16 petabytes of storage.
- Key Hadoop concepts are explained, including jobs, tasks, task attempts, mappers, reducers, and the JobTracker and TaskTracker processes.
- The flow of a MapReduce job is described, from the client submitting the job to the JobTracker, TaskTrackers running tasks on data splits using the mapper and reducer classes, and writing outputs.
This document provides a technical introduction to Hadoop, including:
- Hadoop has been tested on a 4000 node cluster with 32,000 cores and 16 petabytes of storage.
- Key Hadoop concepts are explained, including jobs, tasks, task attempts, mappers, reducers, and the JobTracker and TaskTrackers.
- The process of launching a MapReduce job is described, from the client submitting the job to the JobTracker distributing tasks to TaskTrackers and running the user-defined mapper and reducer classes.
Hadoop is an open source framework for distributed storage and processing of vast amounts of data across clusters of computers. It uses a master-slave architecture with a single JobTracker master and multiple TaskTracker slaves. The JobTracker schedules tasks like map and reduce jobs on TaskTrackers, which each run task instances in separate JVMs. It monitors task progress and reschedules failed tasks. Hadoop uses MapReduce programming model where the input is split and mapped in parallel, then outputs are shuffled, sorted, and reduced to form the final results.
The document provides interview questions and answers related to Hadoop. It discusses common InputFormats in Hadoop like TextInputFormat, KeyValueInputFormat, and SequenceFileInputFormat. It also describes concepts like InputSplit, RecordReader, partitioner, combiner, job tracker, task tracker, jobs and tasks relationship, debugging Hadoop code, and handling lopsided jobs. HDFS, its architecture, replication, and reading files from HDFS is also covered.
Hadoop is an open-source software framework for distributed storage and processing of large datasets across clusters of computers. It provides reliable storage through HDFS and distributed processing via MapReduce. HDFS handles storage and MapReduce provides a programming model for parallel processing of large datasets across a cluster. The MapReduce framework consists of a mapper that processes input key-value pairs in parallel, and a reducer that aggregates the output of the mappers by key.
This document provides an overview of applied recommender systems. It discusses Hadoop, MapReduce, Hive, Mahout and collaborative filtering recommender algorithms. Hadoop is used to process large datasets in parallel across clusters. MapReduce is the programming model and Hive provides a SQL-like interface. Mahout contains machine learning libraries including collaborative filtering algorithms to generate recommendations. Pearson correlation is discussed as an item-item collaborative filtering approach.
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The document contains 31 questions and answers related to Hadoop concepts. It covers topics like common input formats in Hadoop, differences between TextInputFormat and KeyValueInputFormat, what are InputSplits and how they are created, how partitioning, shuffling and sorting occurs after the map phase, what is a combiner, functions of JobTracker and TaskTracker, how speculative execution works, using distributed cache and counters, setting number of mappers/reducers, writing custom partitioners, debugging Hadoop jobs, and failure handling processes for production Hadoop jobs.
This document provides an introduction to MapReduce and Hadoop, including an overview of computing PageRank using MapReduce. It discusses how MapReduce addresses challenges of parallel programming by hiding details of distributed systems. It also demonstrates computing PageRank on Hadoop through parallel matrix multiplication and implementing custom file formats.
Hadoop interview questions for freshers and experienced people. This is the best place for all beginners and Experts who are eager to learn Hadoop Tutorial from the scratch.
Read more here http://softwarequery.com/hadoop/
The document discusses key concepts related to Hadoop including its components like HDFS, MapReduce, Pig, Hive, and HBase. It provides explanations of HDFS architecture and functions, how MapReduce works through map and reduce phases, and how higher-level tools like Pig and Hive allow for more simplified programming compared to raw MapReduce. The summary also mentions that HBase is a NoSQL database that provides fast random access to large datasets on Hadoop, while HCatalog provides a relational abstraction layer for HDFS data.
Hadoop and Pig are tools for analyzing large datasets. Hadoop uses MapReduce and HDFS for distributed processing and storage. Pig provides a high-level language for expressing data analysis jobs that are compiled into MapReduce programs. Common tasks like joins, filters, and grouping are built into Pig for easier programming compared to lower-level MapReduce.
Apache Spark is written in Scala programming language that compiles the program code into byte code for the JVM for spark big data processing.
The open source community has developed a wonderful utility for spark python big data processing known as PySpark.
Stratosphere System Overview Big Data Beers Berlin. 20.11.2013Robert Metzger
Stratosphere is the next generation big data processing engine.
These slides introduce the most important features of Stratosphere by comparing it with Apache Hadoop.
For more information, visit stratosphere.eu
Based on university research, it is now a completely open-source, community driven development with focus on stability and usability.
Getting started with Hadoop, Hive, and Elastic MapReduceobdit
1) The document provides an overview of tools for distributed computing including MapReduce, Hadoop, Hive, and Elastic MapReduce.
2) It discusses getting started with Elastic MapReduce using Python with mrjob or the AWS command line and challenges with getting started with Hive.
3) Potential pitfalls with EMR are also outlined such as JVM memory issues and problems with multiple small output files.
Writing MapReduce Programs using Java | Big Data Hadoop Spark Tutorial | Clou...CloudxLab
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This CloudxLab Writing MapReduce Programs tutorial helps you to understand how to write MapReduce Programs using Java in detail. Below are the topics covered in this tutorial:
1) Why MapReduce?
2) Write a MapReduce Job to Count Unique Words in a Text File
3) Create Mapper and Reducer in Java
4) Create Driver
5) MapReduce Input Splits, Secondary Sorting, and Partitioner
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7) Job Chaining and Pipes in MapReduce
Processing massive amount of data with Map Reduce using Apache Hadoop - Indi...IndicThreads
This document provides an overview of MapReduce and Hadoop. It describes the Map and Reduce functions, explaining that Map applies a function to each element of a list and Reduce reduces a list to a single value. It gives examples of Map and Reduce using employee salary data. It then discusses Hadoop and its core components HDFS for distributed storage and MapReduce for distributed processing. Key aspects covered include the NameNode, DataNodes, input/output formats, and the job launch process. It also addresses some common questions around small files, large files, and accessing SQL data from Hadoop.
The Pregel Programming Model with Spark GraphXAndrea Iacono
GraphX is Apache Spark's API for graph distributed computing based on the Pregel programming model. In this talk we'll see a brief introduction to Pregel and then we'll focus on transforming standard graph algorithms in their distributed counterpart using GraphX to speedup performance in a distributed environment.
Graphs are everywhere! Distributed graph computing with Spark GraphXAndrea Iacono
This document discusses GraphX, a graph processing system built on Apache Spark. It defines what graphs are, including vertices and edges. It explains that GraphX uses Resilient Distributed Datasets (RDDs) to keep data in memory for iterative graph algorithms. GraphX implements the Pregel computational model where each vertex can modify its state, receive and send messages to neighbors each superstep until halting. The document provides examples of graph algorithms and notes when GraphX is well-suited versus a graph database.
Real time and reliable processing with Apache StormAndrea Iacono
Storm is a framework for reliably processing streaming data. It allows defining topologies composed of spouts (data sources) and bolts (processing components). Spouts emit tuples that are processed by bolts which can emit additional tuples. The document describes a topology for processing tweets in real-time to identify top hashtags and display tweets on a map. It includes spouts to fetch tweets and bolts for filtering, counting hashtags, ranking them and storing results to Redis. Storm provides reliability by tracking processing of tuples through a topology using acknowledgments.
The document discusses Java 8 features like lambda expressions, streams, and method references. It provides examples of filtering a list of books by pages or genre using lambda expressions and streams. Lambda expressions allow implementing functional interfaces concisely without anonymous classes. Streams provide a way to process data elements sequentially and support operations like filtering, mapping, matching, reducing, and collecting results.
This document discusses how to build a small distributed search engine using open source software. It describes the main subsystems of a search engine, including a page database, crawler, parser, indexer and link graph database. It then introduces Apache Hadoop and Apache Lucene as open source tools that can be used to build each subsystem in a distributed manner. Hadoop provides HDFS for distributed storage and MapReduce for distributed processing, while Lucene handles full-text indexing and search. The document outlines how Lucene indexes and searches document contents, and how its components can be integrated with HDFS to build a distributed search index and query system.
This document provides an introduction to machine learning concepts including regression analysis, similarity and metric learning, Bayes classifiers, clustering, and neural networks. It discusses techniques such as linear regression, K-means clustering, naive Bayes classification, and backpropagation in neural networks. Code examples and exercises are provided to help readers learn how to apply these machine learning algorithms.
Ansys Mechanical enables you to solve complex structural engineering problems and make better, faster design decisions. With the finite element analysis (FEA) solvers available in the suite, you can customize and automate solutions for your structural mechanics problems and parameterize them to analyze multiple design scenarios. Ansys Mechanical is a dynamic tool that has a complete range of analysis tools.
Alluxio Webinar | 10x Faster Trino Queries on Your Data PlatformAlluxio, Inc.
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As Trino users increasingly rely on cloud object storage for retrieving data, speed and cloud cost have become major challenges. The separation of compute and storage creates latency challenges when querying datasets; scanning data between storage and compute tiers becomes I/O bound. On the other hand, cloud API costs related to GET/LIST operations and cross-region data transfer add up quickly.
The newly introduced Trino file system cache by Alluxio aims to overcome the above challenges. In this session, Jianjian will dive into Trino data caching strategies, the latest test results, and discuss the multi-level caching architecture. This architecture makes Trino 10x faster for data lakes of any scale, from GB to EB.
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- The new Trino file system cache feature overview, including the latest development status and test results
- A multi-level cache framework for maximized speed, including Trino file system cache and Alluxio distributed cache
- Real-world cases, including a large online payment firm and a top ridesharing company
- The future roadmap of Trino file system cache and Trino-Alluxio integration
What is OCR Technology and How to Extract Text from Any Image for FreeTwisterTools
Discover the fascinating world of Optical Character Recognition (OCR) technology with our comprehensive presentation. Learn how OCR converts various types of documents, such as scanned paper documents, PDFs, or images captured by a digital camera, into editable and searchable data. Dive into the history, modern applications, and future trends of OCR technology. Get step-by-step instructions on how to extract text from any image online for free using a simple tool, along with best practices for OCR image preparation. Ideal for professionals, students, and tech enthusiasts looking to harness the power of OCR.
Explore the rapid development journey of TryBoxLang, completed in just 48 hours. This session delves into the innovative process behind creating TryBoxLang, a platform designed to showcase the capabilities of BoxLang by Ortus Solutions. Discover the challenges, strategies, and outcomes of this accelerated development effort, highlighting how TryBoxLang provides a practical introduction to BoxLang's features and benefits.
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1. MapReduce
by examples
The code is available on:
https://github.com/andreaiacono/MapReduce
Take a look at my blog:
https://andreaiacono.blogspot.com/
2. MapReduce by examples
MapReduce is a programming model for
processing large data sets with a parallel,
distributed algorithm on a cluster
[src: http://en.wikipedia.org/wiki/MapReduce]
What is MapReduce?
Originally published in 2004 from Google
engineers Jeffrey Dean and Sanjay Ghemawat
3. MapReduce by examples
Hadoop is the open source implementation of
the model by Apache Software foundation
The main project is composed by:
- HDFS
- YARN
- MapReduce
Its ecosystem is composed by:
- Pig
- Hbase
- Hive
- Impala
- Mahout
- a lot of other tools
4. MapReduce by examples
Hadoop 2.x
- YARN: the resource manager, now called YARN, is now
detached from mapreduce framework
- java packages are under org.apache.hadoop.mapreduce.*
5. MapReduce by examples
MapReduce inspiration
The name MapReduce comes from functional programming:
- map is the name of a higher-order function that applies a given function
to each element of a list. Sample in Scala:
val numbers = List(1,2,3,4,5)
numbers.map(x => x * x) == List(1,4,9,16,25)
- reduce is the name of a higher-order function that analyze a recursive
data structure and recombine through use of a given combining
operation the results of recursively processing its constituent parts,
building up a return value. Sample in Scala:
val numbers = List(1,2,3,4,5)
numbers.reduce(_ + _) == 15
MapReduce takes an input, splits it into smaller parts, execute the code of
the mapper on every part, then gives all the results to one or more reducers
that merge all the results into one.
src: http://en.wikipedia.org/wiki/Map_(higher-order_function)
http://en.wikipedia.org/wiki/Fold_(higher-order_function)
7. MapReduce by examples
How does Hadoop work?
Init
- Hadoop divides the input file stored on HDFS into splits (tipically of the size
of an HDFS block) and assigns every split to a different mapper, trying to
assign every split to the mapper where the split physically resides
Mapper
- locally, Hadoop reads the split of the mapper line by line
- locally, Hadoop calls the method map() of the mapper for every line passing
it as the key/value parameters
- the mapper computes its application logic and emits other key/value pairs
Shuffle and sort
- locally, Hadoop's partitioner divides the emitted output of the mapper into
partitions, each of those is sent to a different reducer
- locally, Hadoop collects all the different partitions received from the
mappers and sort them by key
Reducer
- locally, Hadoop reads the aggregated partitions line by line
- locally, Hadoop calls the reduce() method on the reducer for every line of
the input
- the reducer computes its application logic and emits other key/value pairs
- locally, Hadoop writes the emitted pairs output (the emitted pairs) to HDFS
9. MapReduce by examples
Serializable vs Writable
- Serializable stores the class name and the object representation to the
stream; other instances of the class are referred to by an handle to the
class name: this approach is not usable with random access
- For the same reason, the sorting needed for the shuffle and sort phase
can not be used with Serializable
- The deserialization process creates a new instance of the object, while
Hadoop needs to reuse objects to minimize computation
- Hadoop introduces the two interfaces Writable and WritableComparable
that solve these problem
10. MapReduce by examples
Writable wrappers
Java
primitive
Writable
implementation
boolean BooleanWritable
byte ByteWritable
short ShortWritable
int IntWritable
VIntWritable
float FloatWritable
long LongWritable
VLongWritable
double DoubleWritable
Java class Writable
implementation
String Text
byte[] BytesWritable
Object ObjectWritable
null NullWritable
Java
collection
Writable
implementation
array ArrayWritable
ArrayPrimitiveWritable
TwoDArrayWritable
Map MapWritable
SortedMap SortedMapWritable
enum EnumSetWritable
11. MapReduce by examples
Implementing Writable: the SumCount class
public class SumCount implements WritableComparable<SumCount> {
DoubleWritable sum;
IntWritable count;
public SumCount() {
set(new DoubleWritable(0), new IntWritable(0));
}
public SumCount(Double sum, Integer count) {
set(new DoubleWritable(sum), new IntWritable(count));
}
@Override
public void write(DataOutput dataOutput) throws IOException {
sum.write(dataOutput);
count.write(dataOutput);
}
@Override
public void readFields(DataInput dataInput) throws IOException {
sum.readFields(dataInput);
count.readFields(dataInput);
}
// getters, setters and Comparable overridden methods are omitted
}
12. MapReduce by examples
Glossary
Term Meaning
Job The whole process to execute: the input data,
the mapper and reducers execution and the
output data
Task Every job is divided among the several
mappers and reducers; a task is the job
portion that goes to every single mapper and
reducer
Split The input file is split into several splits (the
suggested size is the HDFS block size, 64Mb)
Record The split is read from mapper by default a line
at the time: each line is a record. Using a class
extending FileInputFormat, the record can
be composed by more than one line
Partition The set of all the key-value pairs that will be
sent to a single reducer. The default
partitioner uses an hash function on the key to
determine to which reducer send the data
14. MapReduce by examples
WordCount
(the Hello World! for MapReduce, available in Hadoop sources)
Input Data:
The text of the book ”Flatland”
By Edwin Abbott.
Source:
http://www.gutenberg.org/cache/epub/201/pg201.txt
We want to count the occurrences of every word
of a text file
15. MapReduce by examples
public static class TokenizerMapper extends Mapper<Object, Text, Text, IntWritable> {
private final static IntWritable one = new IntWritable(1);
private Text word = new Text();
@Override
public void map(Object key, Text value, Context context)
throws IOException, InterruptedException {
StringTokenizer itr = new StringTokenizer(value.toString());
while (itr.hasMoreTokens()) {
word.set(itr.nextToken().trim());
context.write(word, one);
}
}
}
WordCount mapper
16. MapReduce by examples
public static class IntSumReducer extends Reducer<Text,IntWritable,Text,IntWritable>{
private IntWritable result = new IntWritable();
@Override
public void reduce(Text key, Iterable<IntWritable> values, Context context)
throws IOException, InterruptedException {
int sum = 0;
for (IntWritable val : values) {
sum += val.get();
}
result.set(sum);
context.write(key, result);
}
}
WordCount reducer
17. MapReduce by examples
WordCount
a 936
ab 6
abbot 3
abbott 2
abbreviated 1
abide 1
ability 1
able 9
ablest 2
abolished 1
abolition 1
about 40
above 22
abroad 1
abrogation 1
abrupt 1
abruptly 1
absence 4
absent 1
absolute 2
...
Results:
18. MapReduce by examples
MapReduce testing and debugging
- MRUnit is a testing framework based on Junit for unit
testing mappers, reducers, combiners (we'll see later what
they are) and the combination of the three
- Mocking frameworks can be used to mock Context or
other Hadoop objects
- LocalJobRunner is a class included in Hadoop that let us
run a complete Hadoop environment locally, in a single
JVM, that can be attached to a debugger. LocalJobRunner
can run at most one reducer
- Hadoop allows the creation of in-process mini clusters
programmatically thanks to MiniDFSCluster and
MiniMRCluster testing classes; debugging is more difficult
than LocalJobRunner because is multi-threaded and spread
over different VMs. Mini Clusters are used for testing
Hadoop sources.
19. MapReduce by examples
MRUnit test for WordCount
@Test
public void testMapper() throws Exception {
new MapDriver<Object, Text, Text, IntWritable>()
.withMapper(new WordCount.TokenizerMapper())
.withInput(NullWritable.get(), new Text("foo bar foo"))
.withOutput(new Text("foo"), new IntWritable(1))
.withOutput(new Text("bar"), new IntWritable(1))
.withOutput(new Text("foo"), new IntWritable(1))
.runTest();
}
@Test
public void testReducer() throws Exception {
List<IntWritable> fooValues = new ArrayList<>();
fooValues.add(new IntWritable(1));
fooValues.add(new IntWritable(1));
List<IntWritable> barValue = new ArrayList<>();
barValue.add(new IntWritable(1));
new ReduceDriver<Text, IntWritable, Text, IntWritable>()
.withReducer(new WordCount.IntSumReducer())
.withInput(new Text("foo"), fooValues)
.withInput(new Text("bar"), barValue)
.withOutput(new Text("foo"), new IntWritable(2))
.withOutput(new Text("bar"), new IntWritable(1))
.runTest();
}
20. MapReduce by examples
@Test
public void testMapReduce() throws Exception {
new MapReduceDriver<Object, Text, Text, IntWritable, Text, IntWritable>()
.withMapper(new WordCount.TokenizerMapper())
.withInput(NullWritable.get(), new Text("foo bar foo"))
.withReducer(new WordCount.IntSumReducer())
.withOutput(new Text("bar"), new IntWritable(1))
.withOutput(new Text("foo"), new IntWritable(2))
.runTest();
}
MRUnit test for WordCount
21. MapReduce by examples
TopN
Input Data:
The text of the book ”Flatland”
By E. Abbott.
Source:
http://www.gutenberg.org/cache/epub/201/pg201.txt
We want to find the top-n used words of a text file
22. MapReduce by examples
public static class TopNMapper extends Mapper<Object, Text, Text, IntWritable> {
private final static IntWritable one = new IntWritable(1);
private Text word = new Text();
private String tokens = "[_|$#<>^=[]*/,;,.-:()?!"']";
@Override
public void map(Object key, Text value, Context context)
throws IOException, InterruptedException {
String cleanLine = value.toString().toLowerCase().replaceAll(tokens, " ");
StringTokenizer itr = new StringTokenizer(cleanLine);
while (itr.hasMoreTokens()) {
word.set(itr.nextToken().trim());
context.write(word, one);
}
}
}
TopN mapper
23. MapReduce by examples
public static class TopNReducer extends Reducer<Text, IntWritable, Text, IntWritable> {
private Map<Text, IntWritable> countMap = new HashMap<>();
@Override
public void reduce(Text key, Iterable<IntWritable> values, Context context)
throws IOException, InterruptedException {
int sum = 0;
for (IntWritable val : values) {
sum += val.get();
}
countMap.put(new Text(key), new IntWritable(sum));
}
@Override
protected void cleanup(Context context) throws IOException, InterruptedException {
Map<Text, IntWritable> sortedMap = sortByValues(countMap);
int counter = 0;
for (Text key: sortedMap.keySet()) {
if (counter ++ == 20) {
break;
}
context.write(key, sortedMap.get(key));
}
}
}
TopN reducer
24. MapReduce by examples
TopN
the 2286
of 1634
and 1098
to 1088
a 936
i 735
in 713
that 499
is 429
you 419
my 334
it 330
as 322
by 317
not 317
or 299
but 279
with 273
for 267
be 252
...
Results:
25. MapReduce by examples
TopN
In the shuffle and sort phase, the partioner will send
every single word (the key) with the value ”1” to the
reducers.
All these network transmissions can be minimized if
we reduce locally the data that the mapper will emit.
This is obtained by a Combiner.
26. MapReduce by examples
public static class Combiner extends Reducer<Text, IntWritable, Text, IntWritable> {
@Override
public void reduce(Text key, Iterable<IntWritable> values, Context context)
throws IOException, InterruptedException {
int sum = 0;
for (IntWritable val : values) {
sum += val.get();
}
context.write(key, new IntWritable(sum));
}
}
TopN combiner
28. MapReduce by examples
Combiners
If the function computed is
- commutative [a + b = b + a]
- associative [a + (b + c) = (a + b) + c]
we can reuse the reducer as a combiner!
Max function works:
max (max(a,b), max(c,d,e)) = max (a,b,c,d,e)
Mean function does not work:
mean(mean(a,b), mean(c,d,e)) != mean(a,b,c,d,e)
29. MapReduce by examples
Combiners
Advantages of using combiners
- Network transmissions are minimized
Disadvantages of using combiners
- Hadoop does not guarantee the execution of a combiner:
it can be executed 0, 1 or multiple times on the same input
- Key-value pairs emitted from mapper are stored in local
filesystem, and the execution of the combiner could cause
expensive IO operations
30. MapReduce by examples
private Map<String, Integer> countMap = new HashMap<>();
private String tokens = "[_|$#<>^=[]*/,;,.-:()?!"']";
@Override
public void map(Object key, Text value, Context context)
throws IOException, InterruptedException {
String cleanLine = value.toString().toLowerCase().replaceAll(tokens, " ");
StringTokenizer itr = new StringTokenizer(cleanLine);
while (itr.hasMoreTokens()) {
String word = itr.nextToken().trim();
if (countMap.containsKey(word)) {
countMap.put(word, countMap.get(word)+1);
}
else {
countMap.put(word, 1);
}
}
}
@Override
protected void cleanup(Context context) throws InterruptedException {
for (String key: countMap.keySet()) {
context.write(new Text(key), new IntWritable(countMap.get(key)));
}
}
TopN in-mapper combiner
31. MapReduce by examples
private Map<Text, IntWritable> countMap = new HashMap<>();
@Override
public void reduce(Text key, Iterable<IntWritable> values, Context context)
throws IOException, InterruptedException {
int sum = 0;
for (IntWritable val : values) {
sum += val.get();
}
countMap.put(new Text(key), new IntWritable(sum));
}
@Override
protected void cleanup(Context context) throws InterruptedException {
Map<Text, IntWritable> sortedMap = sortByValues(countMap);
int counter = 0;
for (Text key: sortedMap.keySet()) {
if (counter ++ == 20) {
break;
}
context.write(key, sortedMap.get(key));
}
}
TopN in-mapper reducer
33. MapReduce by examples
Mean
Input Data:
Temperature in Milan
(DDMMYYY, MIN, MAX)
01012000, -4.0, 5.0
02012000, -5.0, 5.1
03012000, -5.0, 7.7
…
29122013, 3.0, 9.0
30122013, 0.0, 9.8
31122013, 0.0, 9.0
We want to find the mean max temperature for every month
Data source:
http://archivio-meteo.distile.it/tabelle-dati-archivio-meteo/
34. MapReduce by examples
Mean mapper
private Map<String, List<Double>> maxMap = new HashMap<>();
@Override
public void map(Object key, Text value, Context context)
throws IOException, InterruptedException {
String[] values = value.toString().split((","));
if (values.length != 3) return;
String date = values[DATE];
Text month = new Text(date.substring(2));
Double max = Double.parseDouble(values[MAX]);
if (!maxMap.containsKey(month)) {
maxMap.put(month, new ArrayList<Double>());
}
maxMap.get(month).add(max);
}
@Override
protected void cleanup(Mapper.Context context) throws InterruptedException {
for (Text month: maxMap.keySet()) {
List<Double> temperatures = maxMap.get(month);
Double sum = 0d;
for (Double max: temperatures) {
sum += max;
}
context.write(month, new DoubleWritable(sum));
}
}
35. MapReduce by examples
Is this correct?
Mean mapper
private Map<String, List<Double>> maxMap = new HashMap<>();
@Override
public void map(Object key, Text value, Context context)
throws IOException, InterruptedException {
String[] values = value.toString().split((","));
if (values.length != 3) return;
String date = values[DATE];
Text month = new Text(date.substring(2));
Double max = Double.parseDouble(values[MAX]);
if (!maxMap.containsKey(month)) {
maxMap.put(month, new ArrayList<Double>());
}
maxMap.get(month).add(max);
}
@Override
protected void cleanup(Mapper.Context context) throws InterruptedException {
for (Text month: maxMap.keySet()) {
List<Double> temperatures = maxMap.get(month);
Double sum = 0d;
for (Double max: temperatures) {
sum += max;
}
context.write(month, new DoubleWritable(sum));
}
}
36. MapReduce by examples
Mean
Mapper #1: lines 1, 2
Mapper #2: lines 3, 4, 5
Mapper#1: mean = (10.0 + 20.0) / 2 = 15.0
Mapper#2: mean = (2.0 + 4.0 + 3.0) / 3 = 3.0
Reducer mean = (15.0 + 3.0) / 2 = 9.0
But the correct mean is:
(10.0 + 20.0 + 2.0 + 4.0 + 3.0) / 5 = 7.8
Sample input data:
01012000, 0.0, 10.0
02012000, 0.0, 20.0
03012000, 0.0, 2.0
04012000, 0.0, 4.0
05012000, 0.0, 3.0
Not correct!
37. MapReduce by examples
private Map<Text, List<Double>> maxMap = new HashMap<>();
@Override
public void map(Object key, Text value, Context context)
throws IOException, InterruptedException {
String[] values = value.toString().split((","));
if (values.length != 3) return;
String date = values[DATE];
Text month = new Text(date.substring(2));
Double max = Double.parseDouble(values[MAX]);
if (!maxMap.containsKey(month)) {
maxMap.put(month, new ArrayList<Double>());
}
maxMap.get(month).add(max);
}
@Override
protected void cleanup(Context context) throws InterruptedException {
for (Text month: maxMap.keySet()) {
List<Double> temperatures = maxMap.get(month);
Double sum = 0d;
for (Double max: temperatures) sum += max;
context.write(month, new SumCount(sum, temperatures.size()));
}
}
Mean mapper
This is correct!
38. MapReduce by examples
private Map<Text, SumCount> sumCountMap = new HashMap<>();
@Override
public void reduce(Text key, Iterable<SumCount> values, Context context)
throws IOException, InterruptedException {
SumCount totalSumCount = new SumCount();
for (SumCount sumCount : values) {
totalSumCount.addSumCount(sumCount);
}
sumCountMap.put(new Text(key), totalSumCount);
}
@Override
protected void cleanup(Context context) throws InterruptedException {
for (Text month: sumCountMap.keySet()) {
double sum = sumCountMap.get(month).getSum().get();
int count = sumCountMap.get(month).getCount().get();
context.write(month, new DoubleWritable(sum/count));
}
}
Mean reducer
40. MapReduce by examples
Mean
Result:
R code to plot data:
temp <- read.csv(file="results.txt", sep="t", header=0)
names(temp) <- c("date","temperature")
ym <- as.yearmon(temp$date, format = "%m-%Y");
year <- format(ym, "%Y")
month <- format(ym, "%m")
ggplot(temp, aes(x=month, y=temperature, group=year)) + geom_line(aes(colour = year))
41. MapReduce by examples
Join
Input Data - Users file:
"user_ptr_id" "reputation" "gold" "silver" "bronze"
"100006402" "18" "0" "0" "0"
"100022094" "6354" "4" "12" "50"
"100018705" "76" "0" "3" "4"
…
Input Data - Posts file:
"id" "title" "tagnames" "author_id" "body" "node_type" "parent_id" "abs_parent_id" "added_at" "score" …
"5339" "Whether pdf of Unit and Homework is available?" "cs101 pdf" "100000458" "" "question" "N" "N"
"2012-02-25 08:09:06.787181+00" "1"
"2312" "Feedback on Audio Quality" "cs101 production audio" "100005361" "<p>We are looking for feedback on
the audio in our videos. Tell us what you think and try to be as <em>specific</em> as possible.</p>" "question"
"N" "N" "2012-02-23 00:28:02.321344+00" "2"
"2741" "where is the sample page for homework?" "cs101 missing_info homework" "100001178" "<p>I am sorry if I
am being a nob ... but I do not seem to find any information regarding the sample page reffered to on the 1
question of homework 1." "question" "N" "N" "2012-02-23 09:15:02.270861+00" "0"
...
We want to combine information from the users file with
Information from the posts file (a join)
Data source:
http://content.udacity-data.com/course/hadoop/forum_data.tar.gz
42. MapReduce by examples
@Override
public void map(Object key, Text value, Context context)
throws IOException, InterruptedException {
FileSplit fileSplit = (FileSplit) context.getInputSplit();
String filename = fileSplit.getPath().getName();
String[] fields = value.toString().split(("t"));
if (filename.equals("forum_nodes_no_lf.tsv")) {
if (fields.length > 5) {
String authorId = fields[3].substring(1, fields[3].length() - 1);
String type = fields[5].substring(1, fields[5].length() - 1);
if (type.equals("question")) {
context.write(new Text(authorId), one);
}
}
}
else {
String authorId = fields[0].substring(1, fields[0].length() - 1);
String reputation = fields[1].substring(1, fields[1].length() - 1);
try {
int reputationValue = Integer.parseInt(reputation) + 2;
context.write(new Text(authorId),new IntWritable(reputationValue));
}
catch (NumberFormatException nfe) {
// just skips this record
}
}
}
Join mapper
43. MapReduce by examples
@Override
public void reduce(Text key, Iterable<IntWritable> values, Context context)
throws IOException, InterruptedException {
int postsNumber = 0;
int reputation = 0;
String authorId = key.toString();
for (IntWritable value : values) {
int intValue = value.get();
if (intValue == 1) {
postsNumber ++;
}
else {
reputation = intValue -2;
}
}
context.write(new Text(authorId), new Text(reputation + "t" + postsNumber));
}
Join reducer
45. MapReduce by examples
Join
Result:
R code to plot data:
users <- read.csv(file="part-r-00000",sep='t', header=0)
users$V2[which(users$V2 > 10000,)] <- 0
plot(users$V2, users$V3, xlab="Reputation", ylab="Number of posts", pch=19, cex=0.4)
46. MapReduce by examples
K-means
Input Data:
A random set of points
2.2705 0.9178
1.8600 2.1002
2.0915 1.3679
-0.1612 0.8481
-1.2006 -1.0423
1.0622 0.3034
0.5138 2.5542
...
We want to aggregate 2D points in clusters using
K-means algorithm
R code to generate dataset:
N <- 100
x <- rnorm(N)+1; y <- rnorm(N)+1; dat <- data.frame(x, y)
x <- rnorm(N)+5; y <- rnorm(N)+1; dat <- rbind(dat, data.frame(x, y))
x <- rnorm(N)+1; y <- rnorm(N)+5; dat <- rbind(dat, data.frame(x, y))
53. MapReduce by examples
Hints
- Use MapReduce only if you have really big data: SQL or scripting
are less expensive in terms of time needed to obtain the same
results
- Use a lot of defensive checks: when we have a lot of data, we don't
want the computation to be stopped by a trivial NPE :-)
- Testing can save a lot of time!
54. Thanks!
The code is available on:
https://github.com/andreaiacono/MapReduce
Take a look at my blog:
https://andreaiacono.blogspot.com/