HBase Interview Questions and Answers
1. What is Apache HBase?
HBase is a column oriented database which is used to store the sparse data sets. It is run on the top of HDFS. Apache HBase is a database that runs on a Hadoop cluster.
2.How Clients can access HBase data?
Client can access HBase data through either a native Java API, or through a Thrift or REST gateway, making it accessible by any language.
3.What are the key components of Hbase?
The key components of Hbase are:
- Catalog Tables and
- HBase Master.
4.Define catalog tables in Hbase?
Catalog tables are used to maintain the metadata information.
5.What is the function of HMaster?
HMaster is a MasterServer which is responsible for monitoring all regionserver instancesin a cluster.
6.What is use of tools command?
This command is used to list the hbase surgery tools.
7.What is the use of get() method?
get() method is used to read the data from the table.
8.Define cell in Hbase?
Cell is a smallest unit of hbase table which stores the data in the form of tuple.
9.What is the use of Master Server?
MasterServer is used to assign a region to the region server and also handle the load balancing.
10.How to delete the table with the shell?
To delete table first disable it then delete it.
11.What is decorating Filters?
Decorating filter is used to modify, or extend the filtering process to gain additional control over the returned data.
12.What is region server?
Region server is a file that lists the known region server names.
13.How many compaction types are in Hbase?
There are two types of Compactions in HBase
1.Minor Compaction and
14.What are the operational commands of Hbase?
Operational commands of Hbase are Get, Delete, Put, Increment, and Scan.
15.What is the use of YCSB?
YCSB is used to run comparable workloads against different storage systems.
16.What is the syntax of describe Command?
The syntax of describe command is – hbase> describe tablename
17.What is the use of shutdown command?
Shutdown command is used to shut down the cluster.
18.Define the difference between Hive and Hbase?
Hbase is used to perform record level operations where as hive is used to perform table level operations.
19.What is the most common file system of Hbase?
The most common file system of HBase is HDFS (Hadoop distributed file system)
Lempel-Ziv-Oberhumer (LZO) is a lossless data compression algorithm that is focused on decompression speed, and written in ANSIC.
21.What is the use of truncate command?
Truncate command is used to disable, recreate and drop the specified tables.
22.What YCSB stands for?
YCSB stands for Yahoo! Cloud Serving Benchmark.
23.What is nagios?
Nagios is a very commonly used support tool for gaining qualitative data regarding cluster status. It polls current metrics on a regular basis and compares them with given thresholds.
24.How to open a connection in Hbase?
Following code is used to open a connection in Hbase:
Configuration myConf = HBaseConfiguration.create();
HTableInterface usersTable = new HTable(myConf, “users”);
25.Define Pseudodistributed mode?
A pseudo distributed mode is simply a distributed mode that runs on a single host.
26.What is HBase Shell?
HBase shell is a java API by which we communicate with Hbase.
27.Define compaction in Hbase?
Compaction is a process which is used to merge the Hfiles into the one file and after the merging file is created and then old file is deleted.
28.What is the full form of MSLAB?
MSLAB stands for Memstore-Local Allocation Buffer.
29.What is REST?
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.
30.Which operating system is supported by Hbase?
Hbase supports those operating systems that supports java language. Ex: windows, Linux and etc.
31.What the use is of exists command?
exists command is used to check that the specified table is exists or not.
32.Which type of data Hbase can store?
Hbase can store any type of data that can be converted into bytes.
33.Define HRegionServer in Hbase.
HRegionServer is a RegionServer implementation which is responsible for managing and serving regions.
34.What for S3 stands?
S3 is a one of the file system used by hbase, it stands for Simple Storage Service.
35.What are the fundamental key structures of Hbase?
The fundamental key structures of Hbase are row key and column key.
36.In how many modes HBase can run?
Hbase can run on two different modes, they are 1. Standalone mode and 2. Distributed mode.
37.What is the use of HColumnDescriptor class?
HColumnDescriptor stores the information about a column family like compression settings, Number of versions etc.
38.Which method is used to access HFile directly without using HBase?
HFile.main() method used to access HFile directly without using HBase.
39.What is JMX?
The Java Management Extensions technology is the standard for Java applications to export their status.
40.Which command is used to show the current Hbase user?
whoami command is used to show Hbase user.
41.Define standalone mode in Hbase?
Standalone mode is a default mode of Hbase .In standalone mode, HBase uses local filesystem instead of HDFS and it runs all daemons and a local ZooKeeper in the same JVM process.
42.What is the use of Hbase?
Hbase is used to perform more number of operations per second on a large data sets with random read and write operations.
43.Which command is used to show the version of HBase?
Version command is used to show the version of hbase.
Syntax:- hbase> version
44.What is Hbase Fsck?
HBase comes with a tool called hbck which is implemented by the HBaseFsck class. It provides various command-line switches that influence its behavior.
45.Which filter accepts the pagesize as the parameter in hbase?
PageFilter accepts the pagesize as the parameter.
46.Which command is used to run HBase Shell?
$ ./bin/hbase shell command is used to run the hbase shell.