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Mapr (HP) HBase Developer Certification Questions and Answers (Dumps and Practice Questions)



Question : MapR-FS stores data in abstract entities called _______ that allow for _____________.

: MapR-FS stores data in abstract entities called _______ that allow for _____________.
1. containers, random read access

2. containers, random write access

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4. box, random read access

Correct Answer : Get Lastest Questions and Answer :
Explanation: MapR-FS stores data in abstract entities called containers that allow for random write access. Containers reside in storage pools,
and each storage pool can store many containers. The default container size is 32GB.





Question : Each tablet of a table, along with its corresponding write-ahead log (WAL) files, b-trees, and other associated structures, is stored in _______ container.

: Each tablet of a table, along with its corresponding write-ahead log (WAL) files, b-trees, and other associated structures, is stored in _______ container.
1. one

2. Two

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4. more than one

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Explanation: Each tablet of a table, along with its corresponding write-ahead log (WAL) files, b-trees, and other associated structures, is stored in one container.
Each container (which can be from 16 to 32 GB in size) can store more than one tablet (which default in size to 4096 MB). The recommended practice is to use the default size for
tablets and allow them to be split automatically. Massive tablets can affect synchronization of containers and load balancing across a cluster. Smaller tablets spread data better
across more nodes





Question : Whta is/are advantages of storing tables in conatiners.

A. Scalability of MapR clusters
B. High availability
C. Faster data read process
D. Faster data write process
: Whta is/are advantages of storing tables in conatiners.
1. A,B
2. B,C
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4. A,D
5. B,D

Correct Answer : Get Lastest Questions and Answer :
Explanation: There are two important advantages to storing tablets in containers: MapR clusters are extremely scalable and provide exceptional high availability for
your data.
Scalability of MapR clusters
The location of containers in a cluster is tracked by that cluster's container location database (CLDB). CLDBs are updated only when a container is moved, a node fails, or as a
result of periodic block change reports. The update rate, even for very large clusters, is therefore relatively low. MapR-FS does not have to query the CLDB often, so it can
cache container locations for very long times.
Moreover, CLDBs are very small in comparison to Apache Hadoop namenodes. Namenodes track metadata and block information for all files, and they track locations for all blocks
in every file. Because blocks are typically 200 MB or less in size, the total number of objects that a namenode tracks is very large. CLDBs, however, track containers, which are
much larger objects, so the size of the location information can be 100 to 1000 times smaller than the location information in a namenode. CLDBs also do not track information
about tables and files. Therefore, it is practical to store 10s of exabytes in a MapR cluster, regardless of the number of tables and files.
High availability
Containers are replicated to a configurable number of copies, which are distributed to different nodes in the same cluster as the original or master container. A cluster's
CLDB determines the order in which the replicas are updated. Together, the replicas form a replication chain that is updated transactionally. When an update is applied to a
tablet
in the master container (which is at the head of a replication chain), the update is applied serially to the replicas of that container in the chain. The update is complete
only when all replicas in the chain are updated.
The result of this architecture is that when a node goes down due to hardware failure, the tablets served by that node are available instantly from one of the other nodes that
have the replicated data. In comparison, when a node fails in a busy HBase cluster, it can easily take thirty minutes, if not more, to recover the regions, as the
per-RegionServer write-ahead log needs to be replayed in its entirety before other nodes can start serving any of the regions that were being served by the failed
RegionServer.
MapR can detect the exact point at which replicas diverge, even at a 2 GB per second update rate. MapR randomly picks any one of the three copies as the new master,
rolls back the other surviving replicas to the divergence point, and then rolls forward to converge with the chosen master. MapR can do this on the fly with very little
impact on normal operations.



Related Questions

Question : Which statement is correct regarding the Put operation for inserting the data
 : Which statement is correct regarding the Put operation for inserting the data
1. It doen not replace existing Cell
2. Always creates a new versions of the Cell
3. Default version is the Server's currentTimeMillis
4. Versions can be specified on a per-column basis
5. All of the above




Question : Which of the code segment can be used to explicitely set the version time as

: Which of the code segment can be used to explicitely set the version time as
1. put.add(Bytes.toBytes("cf"), Bytes.toBytes("attr1"), 777, Bytes.toBytes(data));
2. put.add(Bytes.toBytes("cf"), Bytes.toBytes("attr1"), "777", Bytes.toBytes(data));
3. put.add(Bytes.toBytes("cf"), Bytes.toBytes("attr1"), Bytes.toBytes(data), "777");
4. None of the above is correct


Question : Which statement is true regarding the data delete in HBase
table

 : Which statement is true regarding the data delete in HBase
1. Deleted data is not immediately removed
2. Delete creates a tombstone marker
3. Tombstones masks the deleted values
4. Data is removed at major compaction
5. All of the above



Question : Please select the wrong statement regarding the Version delete
 : Please select the wrong statement regarding the Version delete
1. Deleting all the versions older than a certain timestamp can be
performed on a row, column family or a column
2. Delete version at a specific timestamp and can only be performed
on a column
3. For deletion if not timestamp is specified currentTimeMillis is
used
4. For deletion if not timestamp is specified all the versions will
be deleted


Question : Which command in HBase shell you will use to list all user
tables
 : Which command in HBase shell you will use to list all user
1. all tables
2. list
3. describe "Column Family Name"
4. status



Question : Which of the following syntex is correct to create t table
undre fam1
 : Which of the following syntex is correct to create t table
1. create 't1', {NAME => 'fam1'}
2. create 't1', {NAME => 'fam1', VERSIONS => 1}
3. create 't1', 'fam1'
4. All of the above