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Cloudera HBase Certification Questions and Answers (Dumps and Practice Questions)



Question :

Your client application connects to HBase for the first time to perform a write. Which of the following
sequences will it traverse to find the region serving the row range of interest?
:
1. ZooKeeper -> RegionServer -> Region
2. ZooKeeper ->.META. -> RegionServer -> Region
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4. ZooKeeper -> HMaster -> -ROOT- -> .META. -> RegionServer -> Region



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The general flow is that a new client contacts the Zookeeper quorum (a separate cluster of Zookeeper nodes)
first to find a particular row key. It does so by retrieving the server name (i.e. host name) that hosts the -
ROOT- region from Zookeeper. With that information it can query that server to get the server that hosts the .
META. table. Both of these two details are cached and only looked up once. Lastly it can query the .META.
server and retrieve the server that has the row the client is looking for.

Note:
*The .META. table keeps a list of all regions in the system. The .META. table structure is as follows:

Key:
Region key of the format ([table],[region start key],[region id]) Values:
info:regioninfo (serialized HRegionInfo instance for this region) info:server (server:port of the RegionServer
containing this region) info:serverstartcode (start-time of the RegionServer process containing this region)





Question : You have a "Users" table in HBase and you would like to insert a row that consists of a UserID, "jsmith" and
an email address, "jane@example.com". The table has a single Column Family named "Meta" and the row key
will be the user's ID. The shell command you should use to complete this is:
: You have a
1. put `Users', `jsmith70', `jane@example.com'
2. put `Users', `UserID:jsmith70', `Email:jane@example.com'
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4. put `Users', `Meta:UserID', `jsmith70', `Meta:Email, `jane@example.com'



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Explanation: Put a cell ?value? at specified table/row/column and optionally
timestamp coordinates. To put a cell value into table ?t1' at
row ?r1' under column ?c1' marked with the time ?ts1', do:

hbase> put ?t1', ?r1', ?c1', ?value?, ts1

The same commands also can be run on a table reference. Suppose you had a reference
t to table ?t1', the corresponding command would be:

hbase> t.put ?r1', ?c1', ?value?, ts1

2.Create a table called weblog with one column family named stats:
create 'weblog', 'stats'

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put 'weblog', 'row1', 'stats:daily', 'test-daily-value'

4.Add a test value to the weekly column in the stats column family for row 1:
put 'weblog', 'row1', 'stats:weekly', 'test-weekly-value'

5. Add a test value to the weekly column in the stats column family for row 2:
put 'weblog', 'row2', 'stats:weekly', 'test-weekly-value'

In the HBase Shell, you can type put commands to insert a row. put takes 'tableName', 'rowkey','value(optional)', 'columnFamily:columnQualifier', 'value'.
Need to include the column family name: Meta for both columns using the : syntax. Note:
Columns in Apache HBase are grouped into column families. All column members of a column family have the same prefix. For example, the columns courses:history and courses:math are both members of the courses column family. The colon character (:) delimits the column family from the column qualifier . The column family prefix must be composed of printable characters. The qualifying tail, the column family qualifier, can be made of any arbitrary bytes. Column families must be declared up front at schema definition time whereas columns do not need to be defined at schema time but can be conjured on the fly while the table is up an running.





Question :

You have images stored in HBase, which you need to retrieve from within your application. In which format will
your data be returned from an HBase scan?
:
1. Uninterpreted array of bytes
2. Java string literal
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4. Blob datatype




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HBase supports a "bytes-in/bytes-out" interface via Put and Result, so anything that can be converted to an
array of bytes can be stored as a value. Input could be strings, numbers, complex objects, or even images as
long as they can rendered as bytes.



Related Questions

Question :

_________ defines the attributes for a column family
 :
1. HBaseAdmin
2. HTableDescriptor
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Question :

Which of the following is the functionality of the HBaseAdmin class

 :
1. Create and List tables
2. Delete tables
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4. Shut Down the cluster
5. All of the above




Question : Select the correct statement from following
: Select the correct statement from following
1. HBaseAdmin , createTable() method is used to create the table
2. HTableDescriptor used to assign a table name
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4. All 1,2 and 3 are correct
5. Only 3 is correct



Question :

Select the wrong statement in case of HColumnDescriptor
 :
1. HColumnDescriptor defines each column family
2. addFamily method is called once per column family
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4. max version option , can be specified
5. None of the above





Question : Which class is used to open the table


 : Which class is used to open the table
1. HMaster
2. HTable
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4. HColumnDescriptor
5. HBaseAdmin





Question : Client locates the first region of the table by scanning ______

 : Client locates the first region of the table by scanning ______
1. .META
2. -ROOT
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