Hadoop MapReduce Join & Counter- Shikshaglobe

Content Creator: Satish kumar

What is Join in Mapreduce?

Mapreduce Join activity is utilized to consolidate two huge datasets. Notwithstanding, this cycle includes composing loads of code to play out the real join activity. Joining two datasets starts by contrasting the size of each dataset. On the off chance that one dataset is more modest when contrasted with the other dataset, more modest dataset is appropriated to each datum hub in the group. When a participate in MapReduce is circulated, either Mapper or Reducer utilizes the more modest dataset to play out a query for matching records from the enormous dataset and afterward consolidate those records to shape yield records.

Read More: MongoDB Query Document

Sorts of Join

Contingent on the spot where the real join is performed, participates in Hadoop are arranged into-Map-side join - When the join is performed by the mapper, it is called as guide side join. In this sort, the join is performed before information is really consumed by the guide capability. It is obligatory that the contribution to each guide is as a parcel and is in arranged request. Additionally, there should be an equivalent number of parcels and it should be arranged by the join key. Decrease side join - When the join is performed by the minimizer, it is called as lessen side join. There is no need in this join to have a dataset in an organized structure (or divided).Here, map side handling transmits join key and relating tuples of both the tables. As an impact of this handling, all the tuples with same join key fall into similar minimizer which then, at that point, gets the records together with same join key.

Instructions to Join two Data Sets: MapReduce Example

There are two Sets of Data in two Different Files (displayed underneath). The Key Dept_ ID is normal in the two documents. The objective is to utilize MapReduce Join to consolidate these records Instructions to Join 2 Datasets utilizing Hadoop Map Reduce Instructions to Join 2 Datasets utilizing Hadoop Map Reduce Input: The info informational index is a txt record, DeptName.txt and DepStrength.txt

Download Input Files From Here

Guarantee you have Hadoop introduced. Before you start with the MapReduce Join model genuine cycle, change the client to 'hduser' (id utilized while Hadoop setup, you can change to the user is utilized during your Hadoop config ).

What is Counter in MapReduce?

A Counter in MapReduce is a component utilized for gathering and estimating factual data about MapReduce occupations and occasions. Counters monitor different work measurements in MapReduce like the number of tasks that happened and the progress of the activity. Counters are utilized for Problem-finding in Map Reduce. Hadoop Counters are like putting a log message in the code for a guide or decrease. This data could be valuable for finding of an issue in MapReduce work handling. Normally, these counters in Hadoop are characterized in a program (map or lessen) and are increased during execution when a specific occasion or condition (well-defined for that counter) happens. A generally excellent utilization of Hadoop counters is to follow legitimate and invalid records from an info dataset.

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Kinds of MapReduce Counters

There are fundamentally 2 sorts of MapReduce Counters

Hadoop Built-In counters: There are some underlying Hadoop counters which exist per work. The following are implicit counter gatherings

MapReduce Task Counters - Collects task explicit data (e.g., number of information records) during its execution time.

File System Counters - Collects data like number of bytes read or composed by an undertaking

File Input Format Counters - Collects data of various bytes read through File Input Format

File Output Format Counters - Collects data of various bytes composed through File Output Format

Work Counters - These counters are utilized by Job Tracker. Measurements gathered by them incorporate e.g., the quantity of undertaking sent off for a task.

Client Defined Counters

Notwithstanding implicit counters, a client can characterize his own counters utilizing comparative functionalities given by programming dialects. For instance, in Java 'enum' are utilized to characterize client characterized counters.

Counters Example

A model Map Class with Counters to count the quantity of absent and invalid qualities. Input information document utilized in this instructional exercise Our feedback informational collection is a CSV record, Above code bit shows a model execution of counters in Hadoop Map Reduce. Here, Sales Counters is a counter characterized utilizing 'enum'. Counting MISSING and INVALID info records is utilized. In the code piece, on the off chance that 'country' field has zero length, its worth is missing and subsequently comparing counter Sales Counters. MISSING is augmented. Then, in the event that 'deals' field begins with a ", the record is viewed as INVALID. This is shown by augmenting counter Sales Counters. INVALID

HADOOP MAPREDUCE JOIN & COUNTER: Transforming Education and Careers

In today's fast-paced world, where data is abundant and its management is essential, Hadoop MapReduce Join & Counter has emerged as a powerful tool. This article delves into the significance of Hadoop MapReduce Join & Counter, exploring its various aspects, from professional development to its global impact. Let's embark on this journey and understand how this technology is reshaping the educational landscape and career opportunities.

Exploring Different Types of HADOOP MAPREDUCE JOIN & COUNTER

Hadoop MapReduce Join & Counter is a vast field with numerous types and applications. We will explore the different dimensions of this technology, shedding light on its versatility and adaptability.

The Importance of HADOOP MAPREDUCE JOIN & COUNTER in Today's World

Understanding the pivotal role Hadoop MapReduce Join & Counter plays in the modern world is essential. We'll discuss its relevance in managing and analyzing vast amounts of data, from social media trends to business analytics.


For individuals contemplating a career in data science or analysis, the benefits of Hadoop MapReduce Join & Counter are numerous. We'll delve into the advantages it offers, from lucrative job prospects to the satisfaction of solving complex problems.

Learn More: Mongodb Primary Key

How HADOOP MAPREDUCE JOIN & COUNTER Enhance Professional Development

Discover how Hadoop MapReduce Join & Counter can be a game-changer for professionals looking to upskill or switch careers. We'll highlight how it empowers individuals to stay relevant in the rapidly evolving job market.

The Role of HADOOP MAPREDUCE JOIN & COUNTER in Career Advancement

Career advancement is a goal for many, and Hadoop MapReduce Join & Counter can be the key to unlocking new opportunities. We'll discuss how this technology can catapult your career to new heights.

Choosing the Right Education Course for Your Goals

Selecting the right education course is crucial to harness the power of Hadoop MapReduce Join & Counter. We'll provide guidance on choosing the course that aligns with your career objectives.

Online vs. Traditional HADOOP MAPREDUCE JOIN & COUNTER: Pros and Cons

The debate between online and traditional education is ongoing. We'll weigh the pros and cons of both approaches, helping you make an informed decision about your educational journey.

The Future of HADOOP MAPREDUCE JOIN & COUNTER: Trends and Innovations

In a constantly evolving technological landscape, it's essential to stay updated on the latest trends. We'll explore the future of Hadoop MapReduce Join & Counter, offering insights into upcoming innovations.

The Impact of HADOOP MAPREDUCE JOIN & COUNTER on Student Success

Education plays a vital role in shaping the future. We'll analyze how Hadoop MapReduce Join & Counter is impacting student success and transforming the learning experience.

Addressing the Challenges of HADOOP MAPREDUCE JOIN & COUNTER and Finding Solutions

Like any field, Hadoop MapReduce Join & Counter has its challenges. We'll identify these obstacles and present potential solutions to overcome them effectively.

Understanding the Pedagogy and Methodology of HADOOP MAPREDUCE JOIN & COUNTER

Education is not just about content; it's about the methods and pedagogy used. We'll take a closer look at how Hadoop MapReduce Join & Counter is taught and the methodologies that make it effective.

The Global Perspective: HADOOP MAPREDUCE JOIN & COUNTER Around the World

Hadoop MapReduce Join & Counter is not limited to one region; it has a global presence. We'll explore its popularity and adoption worldwide, providing insights into its cultural impact.

HADOOP MAPREDUCE JOIN & COUNTER for Lifelong Learning and Personal Growth

Learning is a lifelong journey, and Hadoop MapReduce Join & Counter is a valuable companion. We'll discuss how it can be used for personal growth and continuous learning.

Funding and Scholarships for HADOOP MAPREDUCE JOIN & COUNTER

Financial constraints should not hinder your education. We'll highlight available funding and scholarship opportunities for aspiring Hadoop MapReduce Join & Counter enthusiasts.

Case Studies: Success Stories from Education Course Graduates

Success stories inspire and motivate. We'll share real-life case studies of individuals who have transformed their careers through Hadoop MapReduce Join & Counter education.

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