HBase Interview Questions and Answers, HBase Interview Questions and Answers Freshers, HBase Interview Questions and Answers, HBase Interview Questions
Before getting on to the HBase interview questions, the student must know that the HBase is a continuously varying field which needs the students as well as professionals to upgrade their skills with the new features and knowledge, to get fit for the jobs associated with HBase. This post related to HBase Interview Questions and Answers, HBase Interview Questions and Answers Freshers, HBase Interview Questions and Answers, HBase Interview Questions will help you let out find all the solutions that are frequently asked in you upcoming HBase interview.
Over thousands of vacancies available for the HBase developers, experts must be acquaintance with all the component of HBase technologies. This is necessary for the students in order to have in-depth knowledge of the subject so that they can have best employment opportunities in the future. Knowing every little detail about HBase is the best approach to solve the problems linked with problem.
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First of all, let us tell you about how the HBase technology is evolving in today’s world and how demanding it is in the upcoming years. In fact, according to one study, most of the companies and businesses have moved to the HBase. Now, you cannot predict how huge the future is going to be for the people experienced in the related technologies.
Hence, if you are looking for boosting up your profile and securing your future, HBase will help you in reaching the zenith of your career. Apart from this, you would also have a lot of opportunities as a fresher.
These questions alone are omnipotent. Read and re-read the questions and their solutions to get accustomed to what you will be asked in the interview. These HBase interview questions and answers will also help you on your way to mastering the skills and will take you to the giant world where worldwide and local businesses, huge or medium, are picking up the best and quality HBase professionals.
This ultimate list of best HBase interview questions will ride you through the quick knowledge of the subject and topics like HDFS and MapReduce framework, Understand Hadoop 2.x Architecture. This HBase interview questions and answers can be your next gateway to your next job as a HBase expert.
These are very Basic HBase Interview Questions and Answers for freshers and experienced both.
Q1: Compare RDBMS with HBase
|Schema||Has a fixed schema||No fixed schema|
|Query Language||Supports structured powerful query language||Simple Query language|
|Transaction Processing||Support ACID transactions.||Is eventually consistent but does not support ACID transactions.|
Q2: Name few other popular column oriented databases like HBase.
A2: CouchDB, MongoDB, Cassandra
Q3: Explain about the data model operations in HBase.
A3: Put Method – To store data in HBase
Get Method – To retrieve data stored in HBase.
Delete Method- To delete the data from HBase tables.
Scan Method –To iterate over the data with larger key ranges or the entire table.
Q4: Does HBase support SQL like syntax?
A4: SQL like support for HBase is not yet available. With the use of Apache Phoenix, user can retrieve data from HBase through SQL queries.
Q5: Should the region server be located on all DataNodes?
A5: Yes. Region Servers run on the same servers as DataNodes.
Q6: What do you understand by compaction?
A6: During periods of heavy incoming writes, it is not possible to achieve optimal performance by having one file per store. Thus, HBase combines all these HFiles to reduce the number of disk seeds for every read. This process is referred to as Compaction in HBase.
Q7: Which one would you recommend for HBase table design approach – tall-narrow or flat wide?
A7: There are several factors to be considered when deciding between flat-wide (millions of columns and limited keys) and tall-narrow (millions of keys with limited columns), however, a tall-narrow approach is often recommended because of the following reasons –
- Under extreme scenarios, a flat-wide approach might end up with a single row per region, resulting in poor performance and scalability.
- Table scans are often efficient over multiple reads. Considering that only a subset of the row data will be required, tall-narrow table design approach will provide better performance over flat-wide approach.
Q8: What is the difference between HBase and HDFS?
A8: HDFS is a local file system in Hadoop for storing large files but it does not provide tabular form of storage. HDFS is more like a local file system (NTFS or FAT). Data in HDFS is accessed through MapReduce jobs and is well suited for high latency batch processing operations.
HBase is a column oriented database on Hadoop that runs on top of HDFS and stores data in tabular format. HBase is like a database management system that communicates with HDFS to write logical tabular data to physical file system. One can access single rows using HBase from billions of records it has and is well-suited for low latency operations. HBase puts data in indexed StoreFiles present on HDFS for high speed lookups.
Q9: Compare HBase & Cassandra
|Basis for the cluster||Hadoop||Peer-to-peer|
|Best suited for||Batch Jobs||Data writes|
Q10: What is S3?
A10: S3 stands for simple storage service and it is a one of the file system used by hbase.
Q11: What is the reason of using HBase?
A11: HBase is used because it provides random read and write operations and it can perform a number of operation per second on a large data sets.
Q12: Define the difference between hive and HBase?
A12: HBase is used to support record level operations but hive does not support record level operations.
Q13: Define standalone mode in HBase?
A13: It is a default mode of HBase. In standalone mode, HBase does not use HDFS—it uses the local filesystem instead—and it runs all HBase daemons and a local ZooKeeper in the same JVM process.
Q14: What is the use of YCSB?
A14: It can be used to run comparable workloads against different storage systems.
Q15: What is regionserver?
A15: It is a file which lists the known region server names.
Q16: What is use of tools command?
A16: This command is used to list the HBase surgery tools.
Q17: Mention what are the key components of Hbase?
- Zookeeper: It does the co-ordination work between client and Hbase Maser
- Hbase Master: Hbase Master monitors the Region Server
- RegionServer: RegionServer monitors the Region
- Region: It contains in memory data store(MemStore) and Hfile.
- Catalog Tables: Catalog tables consist of ROOT and META
Q18: Mention how many operational commands in Hbase?
A18: Operational command in Hbases is about five types
Q19: In Hbase what is column families?
A19: Column families comprise the basic unit of physical storage in Hbase to which features like compressions are applied.
Q20: Explain how does Hbase actually delete a row?
A20: In Hbase, whatever you write will be stored from RAM to disk, these disk writes are immutable barring compaction. During deletion process in Hbase, major compaction process delete marker while minor compactions don’t. In normal deletes, it results in a delete tombstone marker- these delete data they represent are removed during compaction.
Also, if you delete data and add more data, but with an earlier timestamp than the tombstone timestamp, further Gets may be masked by the delete/tombstone marker and hence you will not receive the inserted value until after the major compaction.
Q21: What is decorating Filters?
A21: It is useful to modify, or extend, the behavior of a filter to gain additional control over the returned data. These types of filters are known as decorating filter. It includes SkipFilter and WhileMatchFilter.
Q22: What is the use of truncate command?
A22: It is used to disable, drop and recreate the specified tables.
Q23: Which command is used to run HBase Shell?
A23: ./bin/hbase shell command is used to run the HBase shell. Execute this command in HBase directory.
Q24: Define LZO?
A24: Lempel-Ziv-Oberhumer (LZO) is a lossless data compression algorithm that focuses on decompression speed.
Q25: What is Thrift?
A25: Apache Thrift is written in C++, but provides schema compilers for many programming languages, including Java, C++, Perl, PHP, Python, Ruby, and more.
Q26: What is the use of HColumnDescriptor class?
A26: HColumnDescriptor stores the information about a column family like compression settings, number of versions etc. It is used as input when creating a table or adding a column.
Q27: Is Hbase an OS independent approach?
A27: Yes, it is totally independent of the operating system and the users are free to consider it on Windows, Linux, Unix etc. the only basic requirement is it should have a Java support installed on it.
Q28: How can you make sure of logical grouping of cells in the Hbase?
A28: This can be assured by paying attention to the Row key. The users are free to make sure that all the cells with similar row key can be located to each other and have the presence on a similar server. If the need of defining is realized, the Row key can be considered.
Q29:Why Hbase is a schema-less database?
A29: This is because the users need not to worry about defining the data prior of the time. You only need to define the column family name and nothing else. This makes the Hbase a schema-less database.
Q30: Define TTL in Hbase?
A30: It is basically a technique that is useful when it comes to data retention. It is possible for the users to preserve the version of a cell for a defined time period. The same get deleted automatically upon the completion of such a time.
Q31: Explain about HLog and WAL in HBase.
A31: All edits in the HStore are stored in the HLog. Every region server has one HLog. HLog contains entries for edits of all regions performed by a particular Region Server.WAL abbreviates to Write Ahead Log (WAL) in which all the HLog edits are written immediately.WAL edits remain in the memory till the flush period in case of deferred log flush.
Q32: what is NoSql?
A32: Apache HBase is a type of “NoSQL” database. “NoSQL” is a general term meaning that the database isn’t an RDBMS which supports SQL as its primary access language, but there are many types of NoSQL databases: BerkeleyDB is an example of a local NoSQL database, whereas HBase is very much a distributed database. Technically speaking, HBase is really more a “Data Store” than “Data Base” because it lacks many of the features you find in an RDBMS, such as typed columns, secondary indexes, triggers, and advanced query languages, etc.
Q33: What is the full form of MSLAB?
A33: MSLAB stands for Memstore-Local Allocation Buffer.
Q34: What is REST?
A34: Rest stands for Representational State Transfer which defines the semantics so that the protocol can be used in a generic way to address remote resources. It also provides support for different message formats, offering many choices for a client application to communicate with the server.
Q35: What is the role of Zookeeper in Hbase?
A35: The zookeeper maintains configuration information, provides distributed synchronization, and also maintains the communication between clients and region servers.
Q36: What is HFile ?
A36: The HFile is the underlying storage format for HBase.
HFiles belong to a column family and a column family can have multiple HFiles.
But a single HFile can’t have data for multiple column families
HBase Conclusion Interview FAQs
We know the list of HBase Interview Questions and Answers, HBase Interview Questions and Answers Freshers, HBase Interview Questions and Answers, HBase Interview Questions is overwhelming but the advantages of reading all the questions will maximize your potential and help you crack the interview. The surprising fact is that this HBase interview questions and answers post covers all the basic of the HBase technology and you have to check out the FAQs of different components of HBase too.
However, you will be asked with the questions in the interview related to the above mentioned questions. Preparing and understanding all the concept of HBase technology will help you strengthen the other little information around the topic.
After preparing these interview questions, we recommend you to go for a mock interview before facing the real one. You can take the help of your friend or a HBase expert to find the loop holes in your skills and knowledge. Moreover, this will also allow you in practicing and improving the communication skill which plays a vital role in getting placed and grabbing high salaries.
Remember, in the interview, the company or the business or you can say the examiner often checks your basic knowledge of the subject. If your basics is covered and strengthened, you can have the job of your dream. The industry experts understand that if the foundation of the student is already made up, it is easy for the company to educate the employ towards advance skills. If there are no basics, there is no meaning of having learnt the subject.
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We hope that you enjoyed reading HBase Interview Questions and Answers, HBase Interview Questions and Answers Freshers, HBase Interview Questions and Answers, HBase Interview Questions and all the FAQs associated with the interview. Do not forget to revise all the HBase interview questions and answers before going for the HBase interview. In addition to this, if you’ve any doubt or query associated with HBase, you can contact us anytime. We will be happy to help you out at our earliest convenience. At last, we wish you all the best for your upcoming interview on HBase Technology.