HBase Interview Questions and Answers
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Best HBase Interview Questions and Answers
Are you in search of the frequently asked HBase Interview Questions with Answers? Then you have reached the right destination. Here you will find top 50 frequently asked HBase Interview Questions and Answers. These questions are highly asked by the interviews. We have discussed with the top recruiters and have bought you the set of top 50 HBase Interview Questions and Answers. Aspirants who are preparing to attend an Apache HBase Interview should not miss these questions. All these questions will certainly brush up your Apache HBase knowledge and will mold you confidently to attend and crack the interview. Here, we have almost covered all the topics related to Apache HBase.
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HBase can be defined as the following:
- A column oriented database management system that is being executed in the top of Hadoop Distribute File System (HDFS) is known as HBase.
- HBase is not actually a relational data store and it is also not compatible with SQL or Structured Query Language.
- The master node in HBase operates both the region servers and the clusters in order to store a portion of the table and then handles the functions on the specified data.
The principle components of HBase are as follows:
- ZooKeeper
- RegionServer
- HBase Master or HMaster
- Region
- Catalog Tables
HBase provides all the below listed highlights and so it can be used or preferred:
- It provides highly capable storage system
- It comes under a distributed system to effectively cater huge tables at ease
- It is a column oriented database management system that serves data consistency
- It is horizontally scalable
- It ensures maximum availability and performance
- It is compatible with CRUD (Create, Read, Update and Delete) operations unlike Hadoop Distribute File System (HDFS)
- The main advantage of HBase is that it can handle huge tables that consist of billions of rows and millions of columns
Hbase consist of the following:
- It comprises of a set of tables
- Like a traditional database every table consist of rows and columns
- Every table has a primary key which can be denoted as an element
- All the columns of HBase defines the attributes of an object
Listed below are some of the types of operational or data manipulation commands in HBase:
- Get
- Put
- Delete
- Delete All
- Scan
- Count
- Truncate
The get() method in HBase is used to read the data from the table.
In order to disable, drop or recreate a specific table, the truncate command is used in HBase.
A table is actually splitted into various regions. With the help of Region Servers, a group of regions can be easily served to the clients.
To assign specific region to the region server and to maintain load balancing, this MasterServer is particularly used in HBase.
Column family can be defined as a collection of columns while a row can be defined as the collection of column families.
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The table that maintains the overall metadata information in HBase is known as the catalog table.
A simple storage service and a file system that is utilized by HBase are known as S3.
Hive does not support any record level operations while HBase solely supports all the record level operations.
The process by which we can perform modifications or behavioral extension of a filter in order to acquire an extra or added control over the specific data that is returned is known as decorating filters in HBase. SkipFilter and WhileMatchFilter can be the types of decorating filters in HBase.
There are two modes namely Stabdalone mode and Distributed mode in which HBase can be executed effectively.
Standalone mode is one of the default modes of HBase which makes use of the local file system instead of HDFS or Hadoop Distribute File System. In Standalone mode, both the local ZooKeeper and all the available HBase daemons can be executed in the same JVM process.
An ordinary distributed mode that is executed on a single host is known as the pseudodistributed mode in HBase.
The communication and the configuration information that are being processed among the RegionServer and the client can be maintained effectively with the help of ZooKeeper in HBase. ZooKeeper can also furnish efficient distributed synchronization. ZooKeeper communicates through the sessions in order to retain the state of the server within the cluster.
ZooKeeper can also examine the live and the available servers as every region server in combination with the HBase servers transmits heartbeats at periodic intervals with the ZooKeeper. With ZooKeeper, you can also receive instant sever failure alerts so that you can come up with the recovery steps immediately.
Compaction is one of the processes in which HBase merges some of the HFiles found in a particular region in order to reduce the storage and the number of disk seeks that are required for the read. The types of compaction are as follows:
- Minor Compaction
- Major Compaction
On issuing a delete command in HBase, the columns, column families or the cells will not be instantly deleted instead a tombstone marker will be added. Tombstone is nothing but a particular data which can be stored in addition with the standard data and the main functionality of the Tombstone marker is that it will hide all the data that are deleted.
The data will be deleted only during the time of major compaction. Because in major compaction, the main duty of HBase is that it will combine and recommit all the smaller HFiles of one particular region into a new HFile. During this process, in the new HFile all the identical column families will be arranged together and all the deleted and the expired data will be dropped.
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Version marker, column marker and family marker are the three types of Tombstone markers in HBase.
YCSB is nothing but Yahoo Cloud Serving Benchmark and it can be used to execute workloads that are comparable among the different storage systems available.
The operating systems that support Java which include Linux and Windows are compatible with HBase.
The default blocksize range is 64KB and it is configured per column family. And, this blocksize value can be modified as per necessities.
One of the Java APIs with which we can communicate with HBase is known as the HBase Shell.
On executing ./bin/hbase shell command in the HBase directory, you can run or execute an HBase Shell at ease.
hbase> version is the command which can be used to detect the version of HBase.
whoami is the command that shows the current user of HBase instantly.
Configuration myConf = HBaseConfiguration.create();
HTable table = new HTable(myConf, “users”);
The code listed above is used to open a connection in HBase where “users” denote the table in HBase.
MSLAB can be defined as Memstore-Local Allocation Buffer. In case a request thread is in need of inserting a data into the Memstore, the space for the data will not be assigned by the heap while a memory arena will be assigned to the particular targeted region.
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The full form of LZO is Lempel-Ziv-Oberhumer which is one of the data compression algorithms without any losses which strictly concentrates on the speed of the decompression.
The tool hbck that comes with the HBase can be implemented only with the HBase Fsck class or hbck which is tool that is used to analyze the region consistency, the problems associated with table integrity and to fix all the HBase that are corrupted. HBase Fsck operates on two modes namely:
- A read-only inconsistency identifying mode
- A multi-phase read-write repair mode
REST can be defined as the Representational State Transfer which indicates the semantics such that a protocol can be utilized in a generic manner to point out the remote resources effectively. It is also compatible with various formats of messages such that a client application can communicate with the server at ease.
Apache Thrift is actually written with a simple programming language called C++ which offers schema compilers for a variety of other programming languages which include PHP, Java, Python, Perl, and Ruby and so on.
A support tool that is used to acquire qualitative data in line with the status of the cluster is known as the Nagios which actually pools the active metrics frequently and compares it with the given specific threshold.
The main function of HColumnDescriptor class is that it stores some of the column family details which might include number of versions, compression settings and more which can be utilized as an input while generating a table or while inserting a column.
Listed below are the several filter types that are available in Apache HBase:
- ColumnPrefixFilter
- TimestampsFilter
- PageFilter
- MultipleColumnPrefixFilter
- ColumnPaginationFilter
- SingleColumnValueFilter
- RowFilter
- QualifierFilter
- ValueFilter
- PrefixFilter
- SibgleColumnValueExcludeFilter
- ColumnCountGetFilter
- InclusiveStopFilter
- DependentColumnFilter
- FirstKeyOnlyFilter
- KeyOnlyFilter
- FamilyFilter
- CustomFilter
In HBase, PageFilter is the type of filter that accepts pagesize as its parameter.
JMX stands for Java Management Extensions Technology which is a general standard used in Java to export the required status effectively.
In order to check whether a particular table exists or not, we can use exist command in HBase.
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One of the filters in the HBase that assists in elevating the complete throughput of the clusters is known as the bloom filters.
A cell is nothing but an integral part of an HBase table that consists of a particular segment of information in a tuple format like {row, column, version}.
Currently, HBase does not support any SQL structure but with the help of Apache Phoenix, data from HBase can be retrieved via SQL queries.
The main and the fundamental key structures of HBase are Row key and Column Key.
HBase | Relational Database |
HBase is schema-less | Relational Database comes under schema based structure |
It supports column oriented data store | It supports row-oriented data store |
It stores denormalized data | It stores normalized data |
HBase can actually store any type of data which can be easily converted into bytes.
HFile.main() is the method or command with which we can access Hfiles straight away with the need of HBase.
hbase> describe tablename is the syntax used for describe command.
In order to shut down a cluster in HBase, we can make use of shutdown command.
In order to list the HBase surgery tools, we can make use of the tools command in HBase.
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