This section presents you various set of Mock Tests related to HBase. You can download these sample mock tests at your local machine and solve offline at your convenience. Every mock test is supplied with a mock test key to let you verify the final score and grade yourself.
Q 1 - The data in a cell in Hbase table is identified using the four coordinates. Three of which are − rowkey,column family and column qualifier. The fourth coordinate used to identify each value in a cell is
In every cell Hbase stores the version number for each piece of data along with the value. So the version number is the fourth coordinate which identifies the exact piece of data.
Q 2 - Retrieving a batch of rows in every RPC call made by an API to a HBase database is called a
When a group of records is returned from HBASE database by an API making a RPC call the process is called a scan. The number of rows to be returned by configuring the caching property.
Q 3 - A scan returns bulk of rows. But only a selected few rows can be fetched form a scan using a
The filer clause is used to retrun only a specific set of records and not the entire result of the scan.
Q 4 - Filters in Hbase can be applied to
Filetrs can be applied to rowkeys,column qualifiers and data values.
Q 5 - The command which allows you to change an integer value stored in Hbase cell without reading it first is
The incrementcolumnvlaue() command increments the value stored in a Hbase cell without reading it first.
Q 6 - The number of columns Hbase table can hold is
As the tables are split into chunks and distributed across machines, there is no limit to how many columns they can hold.
Q 7 - A small chunk of data residing in one machine which is part of a cluster of machines holding one Hbase table is known as
A region in Hbase table represents a small chunk of data which is part of a large Hbase table distributed across many servers.
Q 8 - Servers that host regions of a Hbase table are called
The Regionservers are the servers which hold the regions of a Hbase table.
Q 9 - Typically a Hbase Regionserver is collocated with
The Regionservers are collocated with the datanode of a HDFS system.
Q 10 - The size of a individual region is governed by the parameter
The parameter Hbase.region.max.filesize is present in hbase-site.xml and it is configured to decide the size of the region.
Q 11 - When a region becomes bigger in size, it
The region gets split into small regions when it grows bigger in size.
Q 12 - The two tables which are used to find where regions of various tables are hosted are
The –ROOT_ and >META> table hold the data to find the location of regions.
Q 13 - When a client application wants to access a row in a Hbase table it first queries the table
The client first goes to the –ROOT- table which gives further information on which .META. table to refer.
Q 14 - In any mapreduce Job Hbase can be used as a
Hbase can act as source, sink, or shared resource in a mapreduce job.
Q 15 - All MapReduce jobs reading from an Hbase table accept their[K1,V1] pair in the form of
The key and value in a mapreduce job reading from a Hbase table correspond to the [rowkey:scan result] values.
Q 16 - When a map tasks in a mapreduce job reads from the Hbase table, it reads from
Each map tasks reading a Hbase table reads from a region.
Q 17 - The part of a Mapreduce Task which writes to a Hbase table is
In case of reading Hbase through mapreduce the map tasks do the reading but in case of writing to Hbase the reduce tasks do the writing.
Q 18 - While writing to Hbase using the Mapreduce tasks, each reduce tasks writes to
The writes go to the region that is responsible for the rowkey that is being written by the reduce task.
Q 19 - In a reduce-side join the Mapreduce step which is used to collocate the relevant records form the two joining data sets is
A reduce-side join takes advantage of the intermediate Shuffle Step to collocate relevant records from the two sets.
Q 20 - The dis-advantage of reduce-side join is
Reduce-side joins require shuffling and sorting data between map and reduce tasks.
This incurs I/O costs.
Q 21 - In a Map-Side join, we take rows from one table and map it with rows from the other table. The size of one of the table should be
If you join two datasets where at least one of them can fit in memory of the map task,then load the smaller dataset into a hash-table so the map tasks can access it while iterating over the other dataset. In these cases, you can skip the Shuffle and Reduce Steps entirely and emit your final
output from the Map Step.
Q 22 - Hbase stores data in
HBase stores its data on a single file system. It assumes all the RegionServers have access to that file system across the entire cluster.
Q 23 - The number of namespaces, HDFS provides to the regionservers of a Hbase database is
HDFS provides a single namespace to all the RegionServers,and any of them can access the persisted files from any other Regionserver.
Q 24 - Inserting data from one table to another in Hbase is
Given that HBase doesn’t allow inter-table or inter-row transactions.
Q 25 - In Hbase we can create index on
Hbase creates indexes only on the columns that cat as key( the rowkey)
|Question Number||Answer Key|