HBase Interview Questions

In this post we will look at HBase Interview questions. Examples are provided with explanation.

1. What is HBase?
2. What are the features provided by HBase?
3. What are the components of HBase?
4. How many operational commands are used in Hbase?
5. What are Shells in HBase?
6. What is Compaction in HBase?
7. What are the Filters of HBase database?
8. How can we scan filter using HBase shell?
9. How can we distribute files in HBase?
10. What are the types of Tombstone Markers?
11. How can we list all row keys in an HBase Table?
12. How should we copy an existing HBase Table?
13. How can we Delete a Specific Cell in a Table?

What is HBase?

HBase is a databse management system used in running on top of the Hadoop Distributed File System and also helps in providing fault tolerant way in storing data sets in many big data use cases.HBase also provides real time data processing and in reading or writing access in large volumes of data.It is designed in scaling linearly while comprising a set of standard tables through rows and columns.

What are the features provided by HBase?

• HBase provides reading and writing access in highest volume request.
• HBase provides auto failver and reliability.
• HBase columns can be dynamically added and removed.
• HBase has low latency access in data.
• HBase provides MapReduce and Pig integration.
• HBase also provides auto sharding and partitioning.

What are the components of HBase?

Following are the components of HBase:

• Zookeeper used in co-ordinating all the work between HBase Master and the Client.
• HBase Master helps in monitoring Region Server.
• Region Server used in monitoring regions.
• Region used in containing Memory Data Store and HFile.
• Catalog Table helps in containing ROOT and META.

How many operational commands are used in Hbase?

There are 5 types of commands in HBase:
Get
Put
Delete
Scan
Increment

What are Shells in HBase?

HBase consists of Shells that helps in communicating with HBase and also in using Hadoop File System in storing data.
HBase Shell uses commands such as:
status helps in providing new status of HBase.
version helps in providing new versions of HBase.
tabel help used in providing table reference commands.
whoami used in providing information about the user.

What is Compaction in HBase?

HBase Compaction is used in merging HFiles in a single file and can be removed from the database.There are 2 types of Compaction:
Minor Compaction - used in combining small HFiles into large HFiles.It also reuires in reading and reducing many disks reads and overall performance.
Major Compaction - helps in combining StoreFile of one region in single StoreFile and in deleting, removing and expiring versions.

What are the Filters of HBase database?

HBase Filters are used in applying the data of complete rows.Filters used by HBase are as follows:
Page Filter
Time stamp Filter
Family Filter
Row Filter
Qualifier Filter
Column Pagination a Filter
Value Filter
Prefix Filter
Single Column Value Filter
Multiple Column Prefix Filter
Column Count Get Filter
Inclusive Stop Filter
First Key Only Filter
Key Only Filter
Dependent Column Filter

How can we scan filter using HBase shell?

We can scan filters by using the following command:

/
 imports like above
def scan_substr(table,substr,*cols)
    scan table, { columns=> cols, filter=>
        SingleColumnvaluefilter.new
            (Bytes.toBytes(family), Bytes.toBytes(qualifier),
             CompareFilter::CompareOp.valueOf('EQUAL'),
             SubstringComparator.new(substr)) }
//

How can we distribute files in HBase?

What are the types of Tombstone Markers?

There are 3 types of Tombstone Markers:
Column Delete Marker
Family Delete Marker
Version Delete Marker

How can we list all row keys in an HBase Table?

For listing Row keys we can use HBase Shell:

count 'tablename', { interval => 1 }

How should we copy an existing HBase Table?

We can copy HBase Table by using the following command:

snapshot 'SOURCETABLE', 'SOURCETABLE-snapshot'
clone_snapshot 'SOURCETABLE-snapshot', 'newTable'

How can we Delete a Specific Cell in a Table?

We can use the delete command for the following use:

DELETE '<tablename>', '<row>', '<columnname >', '<timestamp>'

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