specialist. Copyright © 2020 Mindmajix Technologies Inc. All Rights Reserved, In This Interview Questions, You Will Learn. The WAL ensures all the changes to the data can be replayed when a RegionServer crashes or becomes unavailable. Every interview is different and the scope of a job is different too. Mindmajix - The global online platform and corporate training company offers its services through the best Along with this, we also offer online instructor-led training on all the major data technologies. You can check Hadoop Terminology for more details. Listed in many Big Data Interview Questions and Answers, the best answer to this is – Open-Source – Hadoop is an open-sourced platform. Basically, to make candidates familiar with the nature of questions that are likely to be asked on the subject of Hive, These Hive scenario based interview questions and answers are formulated. Hadoop Interview Questions. Ans. Hadoop works better for large amounts of data. It can be increased as per your requirements. This mainly saves the time required to load the data into Hive tables. Although it does have some limits to it which can be checked here: https://cwiki.apache.org/confluence/display/Hive/LanguageManual+SubQueries. Q36) Which command is used to format the NameNode? It stores any kind of data. Tell me about a time your workload was very heavy. Ans. Ans. RDBMS supports OLTP(Online Transactional Processing), Hadoop supports OLAP(Online Analytical Processing). However, it is not possible to limit a cluster from becoming unbalanced. Q17) How to decommission (removing) the nodes in the Hadoop cluster? By default, the HDFS block size is 128MB for Hadoop 2.x. There are some of the scenario based question on each topic. hadoop fs -D fs.local.block.size=sizeinKB -put local_name remote_location, ERROR tool.ImportTool: Error during import: No primary key could be found for table . Yes, now Hive support IN or EXIST operators. In Hadoop 2.x, we have both Active and passive NameNodes. HDFS Block is the physical division of the disk which has the minimum amount of data that can be read/write, while MapReduce InputSplit is the logical division of data created by the InputFormat specified in the MapReduce job configuration. RecordReader in Hadoop uses the data from the InputSplit as input and converts it into Key-value pairs for Mapper. In this case, we can apply the partition based on the state. As of 4 th, April 2015 - there are about 50,000 job openings for Hadoop Developers across the world with close to 25,000 openings in the US alone.Of the 3000 Hadoop students that we have trained so far, the most popular blog article request was one on hadoop interview questions. –columns “first_name, last_name, created_date” Build a new class that extends Partitioner Class. Accesses records from tables using SQL queries. However, you can quite easily end u saying the wrong thing and end up not getting the job as a result! Ans. It provides multiple namespaces in the cluster to improve scalability and isolation. RDD(Resilient Distributed Datasets) is a fundamental data structure of Spark. It is important for MapReduce as in the sorting phase the keys are compared with one another. –connect jdbc:mysql://localhost/ dbname\ SELECT a.key, a.value Big Data refers to a large amount of data that exceeds the processing capacity of conventional database systems and requires a special parallel processing mechanism.This data can be either structured or unstructured data. Ans. This can apply if you are pointing multiple schemas (tables or views) at a single data set or if you are iterating through various possible schemas. So, if you have gained some experience, don’t forget to cover command based, scenario-based, real-experience based questions. –target-dir /user/root/user_data \ Ans. Add the custom partitioner to the job as a config file or by using the method set Partitioner. Ans. If I use ‘Put’ command to copy the file from non-local location to HDFS, then it showing the error like there is no such source file in the local file system. These Hadoop interview questions specify how you implement your Hadoop knowledge and approach to solve given big data problem. RDBMS cannot store and process a large amount of data. Interested in Apache Hadoop as a building block of your tech career? Schema of the data is known in RDBMS and it always depends on the structured data. Q37) How a client application interacts with the NameNode? It interprets the results of how a record should be processed by allowing Hive to read and write from a table. What is the default block size in Hadoop and can it be increased?” txt_align=”justify”]Ans: The default block size in Hadoop 1 is 64 MB while in Hadoop 2, it is 128MB. Apache Hadoop and Mapreduce Interview Questions has a collection of 120+ questions with answers asked in the interview for freshers and experienced (Programming, Scenario-Based, Fundamentals, Performance Tuning based Question and Answer). If you're looking for Apache Spark Interview Questions for Experienced or Freshers, you are at right place. Steps involved in Hadoop job submission: Ans. So it is similar to what you call Hive Query optimization. Hadoop job client submits the job jar/executable and configuration to the ResourceManager. amzn_assoc_region = "US"; Integrate Oozie with the Hadoop stack, which supports several types of Hadoop jobs such as Streaming MapReduce, Java MapReduce, Sqoop, Hive, and Pig. It is mainly responsible for managing a collection of submitted applications. Apache Oozie is a scheduler which controls the workflow of Hadoop jobs. In this Big Data Hadoop Interview Questions blog, you will come across a compiled list of the most probable Big Data Hadoop questions that recruiters ask in the industry. Moreover, both freshers, as well as experienced candidates, can refer to this blog. The process of translating objects or data structures state into binary or textual form is called Avro Serialization. /usr/hive/warehouse is the default location where Hive stores the table data in HDFS. For aggregation, we need the output from all the mapper functions, which is not possible during the map phase as map tasks will be running in different nodes, where data blocks are present. We make learning - easy, affordable, and value generating. It allows the code to be rewritten or modified according to user and analytics requirements. In Hadoop 1.x, NameNode is the single point of failure. Combiner: Combiner works like a mini reducer in Map phase which takes the input from map phase. So in –copyToLocal command, the destination has to be the local file system. Hadoop follows the schema on reading policy, Hadoop is a free and open-source framework, A small block size of data (like 512 bytes), Reads data sequentially after single seek. FROM B); SELECT a.key, a.val Ans. The number of partitions is equal to the number of reducers. 44. Q16) How to commission (adding) the nodes in the Hadoop cluster? As you saw, put can do what copyFromLocal is doing but the reverse is not true. Once combiner functionality is executed (if required) then the output is passed to the reducer phase. So in partition and combiner, combiner comes first and then partition. Hadoop Hive Interview Questions And Answers For Freshers, Experienced, hive scenario based interview questions, tricky hive interview questions BLACK FRIDAY OFFER: Flat 50% Off with Free Self Learning Course | Use Coupon BLACKFRIDAY50 COPY CODE For example, the data files are read and processed by an existing program that doesn’t lock the files. This has been a guide to List of Informatica Scenario based Interview Questions and answers so that the candidate can crackdown these Interview Questions easily. Often questions are asked based on a scenario or problem that your interviewer faced in the past and will be interested to check out the way in which solve the problem. Thus, one must have the proper knowledge of the cluster based on the current scenario which depends on the following factor: The actual data size to be store is around 600TB. The job configuration requires the following: Ans. During March 2014, there were approximately 17,000 Hadoop Developer jobs advertised online. This is an open ended question and the interviewer is trying to see the level of hands-on experience you have in solving production issues. It is defined as a language-independent schema (written in JSON). It is a file-level computer data storage server connected to a computer network, provides network access to a heterogeneous group of clients. amzn_assoc_search_bar = "true"; The site has been started by a group of analytics professionals and so far we have a strong community of 10000+ professionals who are either working in the data field or looking to it. Q12) What is the default replication factor? It implements mapping inputs directly into the output. Ans. amzn_assoc_ad_type = "smart"; And so each time you’ll load a file, you need to specify the state value as shown below. HDFS (Hadoop Distributed File System) is the primary data storage unit of Hadoop. It receives inputs from the Map class and passes the output key-value pairs to the reducer class. Apache Hadoop and Mapreduce Interview Questions has a collection of 120+ questions with answers asked in the interview for freshers and experienced (Programming, Scenario-Based, Fundamentals, Performance Tuning based Question and Answer). Client applications associate the Hadoop HDFS API with the NameNode when it has to copy/move/add/locate/delete a file. 10 top interview questions asked in recent interviews. So you have finally found your dream job in Hadoop Admin but are wondering how to crack the Hadoop Admin Interview and what could be the probable Hadoop Admin Interview Questions. Hadoop fsck command is used for checking the HDFS file system. hive>LOAD DATA INPATH ‘/hdfs path of the file’ INTO TABLE tblname PARTITION(state=”Illions”). You can also subscribe without commenting. You can use these Hadoop interview questions to prepare for your next Hadoop Interview. Ans. The Purpose of Distributed Cache in the MapReduce framework is to cache files when needed by the applications. Pig Latin is a high-level scripting language while MapReduce is a low-level data processing paradigm. Writables are interfaces in Hadoop. Automatic parallelization and distribution. So, it is not possible for multiple users or processes to access it at the same time. –columns “first_name, last_name, created_date” I will list those in this Hadoop scenario based interview questions post. This definitive list of top Hadoop Interview Questions will cover the concepts including Hadoop HDFS, MapReduce, Pig, Hive, HBase, Spark, Flume, and Sqoop. Characteristics of Big Data: Volume - It represents the amount of data that is increasing at an exponential rate i.e. Q5) What is the difference between a regular file system and HDFS? Don't subscribe It is a compressed binary file format optimized for passing the data between outputs of one MapReduce job to the input of some other MapReduce job. .hdfs dfsadmin -point topology is used for printing the topology. Big Data refers to a large amount of data that exceeds the processing capacity of conventional database systems and requires a special parallel processing mechanism. This course is intended to help Apache Hadoop and Mapreduce Career Aspirants to prepare for the interview. whether it really works?? Update the network addresses in the dfs.exclude and mapred.exclude, Update the Namenode: $ Hadoop dfsadmin -refreshNodes, Update the JobTracker: Hadoop mradmin -refreshNodes, Cross-check the Web UI it will show “Decommissioning in Progress”. Active NameNode works and runs in the cluster. Let’s make it the only destination for all Hadoop interview questions and answers. For the first two questions. Can we use LIKE operator in Hive?”]Yes, Hive supports LIKE operator, but it doesn’t support multi-value LIKE queries like below-. Yes, we can build “Spark” for any specific Hadoop version. Here I have compiled a list of all Hadoop scenario based interview questions and tried to answer all those Hadoop real time interview questions. It periodically creates the checkpoints of filesystem metadata by merging the edits log file with FsImage file. Follow this hadoop developer interview guide and prepare yourself for the interview. In such cases, dynamic partitions are used. Here I have compiled a list of all Hadoop scenario based interview questions and tried to answer all those Hadoop real time interview questions. ResourceManager then distributes the software/configuration to the slaves. The following steps need to be executed to resolve the NameNode issue and make the Hadoop cluster up and running: Ans. TIP #1 – Scenario-based interview questions appear to be relatively easy to answer upon first inspection. Question2: What are the daemons required to run a Hadoop cluster? While you’re on the job hunt, Hadoop developer interview questions will explore whether you have the technical chops with this open-source framework, especially if you’re going for a role such as data engineer or B.I. amzn_assoc_placement = "adunit0"; HDFS Federation enhances the present HDFS architecture through a clear separation of namespace and storage by enabling a generic block storage layer. Here is the solution of what to do when you don’t have a primary key column in RDBMS, and you want to import using Sqoop. Usually, we do dynamic partition when we do kind of ETL jobs. The Hadoop Developer Interview guide has more complex and difficult to answer scenario based questions than what is shown below. Identity Mapper is a default Mapper class which automatically works when no Mapper is specified in the MapReduce driver class. Hadoop is an open-source framework used for storing large data sets and runs applications across clusters of commodity hardware. Ans. Q22) List the different types of Hadoop schedulers. Ans. The concept of choosing closer data nodes based on racks information is called Rack Awareness. [/vc_cta][/vc_column][/vc_row][vc_row][vc_column][vc_cta h2=”3. Q35) What is the main functionality of NameNode? This entry was posted in Sqoop Interview Questions and Answers and tagged Sqoop Interview Questions and Answers for Experienced on January 2, 2015 by Siva In this post we will provide some practical Sqoop Interview Questions and Answers for experienced hadoop developers. It uses MapReduce to effect its distribution, reporting, recovery,  and error handling. The Various HDFS Commands are listed bellow. What do the four Vs of Big Data denote? –table user \ Update the network addresses in the dfs.include and mapred.include, Update the NameNode: Hadoop dfsadmin -refreshNodes, Update the Jobtracker: Hadoop mradmin-refreshNodes. It performs local reduce function on mapper result before they are distributed further. The language used in this platform is called Pig Latin. Q19) What is the difference between active and passive NameNodes? How do you debug a performance issue or a long running job? Ans. When you have cached a file for a job, the Hadoop framework will make it available to each and every data node where map/reduces tasks are operating. It displays the tree of racks and DataNodes attached to the tracks. How do you debug a performance issue or a long running job? MapReduce Programming model is language independent, Distributed programming complexity is hidden, Manages all the inter-process communication, The application runs in one or more containers, Job’s input and output locations in the distributed file system, Class containing the map function and reduce function, JAR file containing the reducer, driver, and mapper classes. 9. According to Forbes, 90% of global organizations report their investments in Big Data analytics, which clearly shows that the career for Hadoop professionals is very promising right now and the upward trend will keep progressing with time. Ans. Hadoop is Java-based programming framework which is open source and it facilitates the dispensation and availability of storage space for extremely large data sets in a scattered counting and computing environment. In static partition, you need to specify the partition column value in each load.For example, let’s say we are having a table with the population of USA and the file is based on the state. I am not sure when this article was written, but Hive supports IN and EXISTS at least since 2014. Replies to my comments Here you should ensure that the partition column is the last column of the non-partitioned table. Rest of the content is very good and helps revise the concepts. Ans. Introduction To Hadoop – Big Data Overview, HDFS Architecture, Features & How To Access HDFS - Hadoop. When to use external and internal tables in Hive?”]Use EXTERNAL tables when: Data will be available directly for all partition when you will put it through command and not manually. Q6) What are the Hadoop daemons and explain their roles in a Hadoop cluster? Through this list of interview questions you will learn the Sqoop basic commands, import control commands, importing data from particular row/column, role of JDBC in Sqoop setup,.. Read More Sqoop meta store, failure exception handling and more.Learn Big Data Hadoop from Intellipaat Hadoop training and fast-track your career. amzn_assoc_title = "My Amazon Picks"; It takes the input from mapper phase or Combiner phase (if used) and then sends it across the responsible reducer based on the key. Ans. Do share those Hadoop interview questions in the comment box. But, before starting, I would like to draw your attention to the Hadoop revolution in the market. Q8) How can you skip the bad records in Hadoop? A serializable object which executes a simple and efficient serialization protocol, based on DataInput and DataOutput. The interview panel asks the candidates who apply for hadoop developer or hadoop testing a few general questions as well as hadoop scenario based questions to check knowledge. These include HDFS, MapReduce, YARN, Sqoop, HBase, Pig and Hive. It caches read-only text files, jar files, archives, etc. Hive should not own data and control settings, dirs, etc., you may have another program or process that will do those things. RAID (redundant array of independent disks) is a data storage virtualization technology used for improving performance and data redundancy by combining multiple disk drives into a single entity. What is the difference between Static and Dynamic Partition”]Partition in Hive is an important concept and is one of the best Hive performance tuning techniques as well. NAS is a high-end storage device which includes a high cost. hadoop fs -put … . In order to give a balance to a certain threshold among data nodes, use the Balancer tool. Connect with her via LinkedIn and Twitter . HDFS divides data into blocks, whereas MapReduce divides data into input split and empower them to mapper function. Apache Sqoop is a tool particularly used for transferring massive data between Apache Hadoop and external datastores such as relational database management, enterprise data warehouses, etc. Ans: IBM has a nice, simple explanation for the four critical features of big data: Volume –Scale of data specialist. According to research Apache Spark has a market share of about 4.9%. In dynamic partition, we should not specify the partition column values in each load statement. Now, configure DataNodes and clients, so that they can acknowledge the new NameNode, that is started. We will be covering Hadoop scenario based interview questions, Hadoop interview questions for freshers as well as Hadoop interview questions and answers for experienced. Ans. Surgnisirply well-written and informative for a free online article. If you delete an external table the file still remains on the HDFS server. It is designed to provide high table-update rates and a fault-tolerant way to store a large collection of sparse data sets. Q1. Top Hadoop Interview Questions: These are some of the most common Hadoop interview questions that you can face during an interview. 44. The syntax for running the MapReduce program is. The below image from Yahoo depicts the operation beautifully. This data can be either structured or unstructured data. customizable courses, self paced videos, on-the-job support, and job assistance. The first and best function of Sqoop? Thus, one must have the proper knowledge of the cluster based on the current scenario which depends on the following factor: The actual data size to be store is around 600TB. The reason for asking such Hadoop Interview Questions is to check your Hadoop skills. Here is the blog on Apache Hive interview questions in Hadoop Interview Questions series. Static Partition: Usually while loading big files in Hive tables, Static Partition is preferred. NameNode chooses the Datanode which is closer to the same rack or nearby rack for reading/Write request. SerDe is a combination of Serializer and Deserializer. This has been a guide to List of Informatica Scenario based Interview Questions and answers so that the candidate can crackdown these Interview Questions easily. Ans. Where the Mapper’s Intermediate data will be stored?” txt_align=”justify”]. Remove the Nodes from include file and then run: Hadoop dfsadmin-refreshNodes, Hadoop mradmin -refreshNodes. If you are looking to advertise here, please check our advertisement page for the details. Rack Awareness is the algorithm used for improving the network traffic while reading/writing HDFS files to Hadoop cluster by NameNode. Because it is keep on searching in the local file system for the source file rather than HDFS. 250+ Hadoop Administration Interview Questions and Answers, Question1: How will you decide whether you need to use the Capacity Scheduler or the Fair Scheduler? Ans. Scenario based questions are certainly common at this stage. The MapReduce Partitioner manages the partitioning of the key of the intermediate mapper output. –split-by created_date. If you have ever appeared for the Hadoop interview, you must have experienced many Hadoop scenario based interview questions. Ex: replication factors, block location, etc. These Scenario-based Hadoop interview questions will give you an idea. Check out these popular Big Data Hadoop interview questions mentioned below: Q1. Moreover, both freshers, as well as experienced candidates, can refer to this blog. Explain the different features of Hadoop. This Apache Spark Interview Questions blog will prepare you for Spark interview with the most likely questions you are going to be asked in 2020. Q15) What are the limitations of Hadoop 1.0? This is an open ended question and the interviewer is trying to see the level of hands-on experience you have in solving production issues. It maintains configuration data, performs synchronization, naming, and grouping. Ans. hive> INSERT INTO TABLE Y PARTITION(state) SELECT * from X; Pig Join- A Beginners guide to Pig Joins & Examples, A Definitive Guide To Hive Performance Tuning- 10 Excellent Tips, Hadoop scenario based interview questions, Scenario Based Hadoop Interview Questions, Scenario Based Hadoop Interview Questions & Answers, Understanding the Rising Cost of Higher Education, Citi Bank Data Science Interview Questions, 5 Top Hadoop Alternatives to Consider in 2020. In DataNodes, RAID is not necessary as storage is achieved by replication between the Nodes. Q23)  How to keep an HDFS cluster balanced? FROM a Here are the few parameters, you need to take care while dealing with CBO in Hive. This course is intended to help Apache Hadoop and Mapreduce Career Aspirants to prepare for the interview. SequenceFileInputFormat is the input format used for reading in sequence files. Q20) How will you resolve the NameNode failure issue? You can get the partition column name from file name without reading the whole file. Ans. Spot the difference in these answers: Ans. amzn_assoc_ad_mode = "manual"; This is one of those scenarios questions that judge prioritization skills. The interviewer wants to know how you handle pressure and situations that require you to think independently. Apache Flume is a service/tool/data ingestion mechanism used to collect, aggregate, and transfer massive amounts of streaming data such as events, log files, etc., from various web sources to a centralized data store where they can be processed together. Q3) What is Hadoop and list its components? Let’s start with some major Hadoop interview questions and answers. Ans. Want to become a Hadoop Developer? Accesses data from HBase tables using APIs and MapReduce. Join our subscribers list to get the latest news, updates and special offers delivered directly in your inbox. I have covered the interview questions from … Discuss one important decision you made in your last role and the impact that decision had. Q21) What is a Checkpoint Node in Hadoop? Q7) What is Avro Serialization in Hadoop? As this is not the default mode of Hive and so you need to set the following two properties in Hive-site.XML file. The scenario-based interview questions below measure your time management. Basically, to make candidates familiar with the nature of questions that are likely to be asked on the subject of Hive, These Hive scenario based interview questions and answers are formulated. Ans. Often questions are asked based on a scenario or problem that your interviewer faced in the past and will be interested to check out the way in which solve the problem. As this is the default mode of Hive and so you can find the below property set in hive-site.xml. FROM a LEFT SEMI JOIN b on (a.key = b.key), The major difference between the internal and external tables are-. Introduction To Hadoop Admin Interview Questions And Answers. It allocates the resources (containers) to various running applications based on resource availability and configured shared policy. Whether it could be structured, unstructured, or semi-structured. The data is also used outside of Hive. Please specify one with –split-by or perform a sequential import with ‘-m 1’. Ans. Here are the scripts which you can use to import an RDBMS table in Hadoop using Sqoop when you don’t have a primary key column. IdentityMapper.class is used as a default value when JobConf.setMapperClass is not set. Q14) Compare HDFS (Hadoop Distributed File System) and NAS (Network Attached Storage)? It performs all the administrative tasks on the HDFS. It executes Hadoop jobs in Apache Spark, MapReduce, etc. Created by HdfsTutorial. Hence, this reduces development time by almost 16 times. Ans. Without much complex Java implementations in MapReduce, programmers can perform the same implementations very easily using Pig Latin. I hope these questions will be helpful for your Hadoop job and in case if you come across any difficult question in an interview and unable to find the best answer please mention it in the comments section below. Scenario based questions are certainly common at this stage. We here at Hdfs Tutorial, offer wide ranges of services starting from development to the data consulting. Consider the replication factor is 3 for data blocks on HDFS it means for every block of data two copies are stored on the same rack, while the third copy is stored on a different rack. Troubleshooting and optimizations questions are really common in Hadoop … Hadoop is Java-based programming framework which is open source and it facilitates the dispensation and availability of storage space for extremely large data sets in a scattered counting and computing environment. Ans. Hope it clarified the difference between the static partition and dynamic partition in Hive. How Much Java Knowledge Is Required To Learn Hadoop? [/vc_cta][/vc_column][/vc_row][vc_row][vc_column][vc_cta h2=”12. SELECT * FROM user_table WHERE first_name LIKE ANY ( ‘root~%’ , ‘user~%’ ); WHERE table2.product LIKE concat(‘%’, table1.brand, ‘%’). Partition: Partition comes into picture when you are using more than one reducer. As we know, there are two type of partition in Hive and those are-. The new NameNode will start serving the client once it has completed loading the last checkpoint FsImage and enough block reports from the DataNodes. –password root \ For each logically equivalent plan, assign a cost. About 57% of hiring managers list that as a must. –table user \ It is a data processing engine which provides faster analytics than Hadoop MapReduce. If your table doesn’t have the primary key column, you need to specify -m 1 option for importing the data, or you have to provide –split-by argument with some column name. They are: Ans. sqoop import \ Troubleshooting and optimizations questions are really common in Hadoop interviews. Reducers always run in isolation and the Hadoop Mapreduce programming paradigm never allows them to communicate with each other. [/vc_cta][/vc_column][/vc_row][vc_row][vc_column][vc_cta h2=”14. Left Semi Join performs the same operation IN do in SQL. The scenario-based interview questions below measure your time management. Writes are fast in Hadoop because no schema validation happens during HDFS write. Dynamic Partition: Here every row of the data available in the file is read and partition is getting done through a MapReduce job. Meta data is maintained on master node and deleting an external table from HIVE, only deletes the metadata not the data/file. By providing us with your details, We wont spam your inbox. It can easily store and process a large amount of data compared to RDBMS. There are different arguments that can be passed with this command to emit different results. Look at Sqoop tutorial before you move further. These Hadoop interview questions specify how you implement your Hadoop knowledge and approach to solve given big data problem. ResourceManager then scheduling tasks and monitoring them. It is designed to work for the MapReduce paradigm. Hence, that will help you face your Hadoop job interview. –target-dir /user/root/user_data \ HDFS High availability is introduced in Hadoop 2.0. Ans. Q2) Explain Big data and its characteristics. MapReduce framework is used to write applications for processing large data in parallel on large clusters of commodity hardware. MRV2/YARN (ResourceManager & NodeManager), Its schema is more flexible and less restrictive, Suitable for both structured and unstructured data. Scenario: Suppose I have installed Apache Hive on top of my Hadoop cluster using default metastore configuration. MapReduce is a programming model used for processing and generating large datasets on the clusters with parallel and distributed algorithms. There are a lot of opportunities from many reputed companies in the world. Pig offers various built-in operators for data operations like filters, joins, sorting, ordering, etc., while to perform these same functions in MapReduce is an enormous task. It means providing support for multiple NameNodes to the Hadoop architecture. So the main difference between -copyFromLocal and -put commands is, in -copyFromLocal, the source has to be the local file system which is not mandatory for –put command. Scenario: Suppose I have installed Apache Hive on top of my Hadoop cluster using default metastore configuration. Deleting the table deletes the metadata & data from master-node and HDFS respectively. Let’s start with some major Hadoop interview questions and answers. Streaming data is gathered from multiple sources into Hadoop for analysis. To make this conceivable, Hadoop Tutorial uses a conveyed record system which separates input information and sends division of unique […]. –password root \ The basic parameters of Mapper are listed below: Ans. You want Hive to completely manage the lifecycle of the table and data, Create a non-partitioned table X and load the data, Now create a partitioned table Y and specify the partition column (say state). Hadoop allows firms to run data applications on large, often distributed hardcase clusters. In Apache Hadoop, if nodes do not fix or diagnose the slow-running tasks, the master node can redundantly perform another instance of the same task on another node as a backup (the backup task is called a Speculative task). This is one of those scenarios questions that judge prioritization skills. For example, let’s say you are loading a table X from some copy command and then copy the data from table X to table Y after some calculation and further some ETL processes. Top 100+ Hadoop Interview Questions and Answers - What is Hadoop | What are the components of HDFS and YARN | Why Hadoop is used for big data | What is fsck | How to recover a NameNode when it is down | What is the difference between Hadoop and RDBMS | What are the features of Hadoop | What are the core components of Hadoop | What are the running modes of Hadoop | Why do we need Data … 1. Ans. We fulfill your skill based career aspirations and needs with wide range of –connect jdbc:mysql://localhost/dbname \ The purpose of the DataNode block scanner is to operate and periodically check all the blocks that are stored on the DataNode. Writables are used for creating serialized data types in Hadoop. amzn_assoc_linkid = "e25e83d3eb993b259e8dbb516e04cff4"; Generally, the daemon is nothing but a process that runs in the background. WHERE a.key in It is a distributed file system used for storing data by commodity hardware. The reason for asking such Hadoop Interview Questions is to check your Hadoop skills. Q27) What is a rack-aware replica placement policy? –username root \ 1. Real Time Hadoop Interview Questions From Different Readers 3 This entry was posted in Hadoop Interview Questions for experienced and freshers Java Interview Questions MapReduce Interview Questions Pig Interview Questions for experienced and freshers on July 17, 2015 by Siva You add the partition column manually and move the file into the partition table manually.