Hadoop Questions and Answers – Schema Design in HBase

This set of Questions & Answers focuses on “Schema Design in HBase”.

1. The minimum number of row versions to keep is configured per column family via _____________
a) HBaseDecriptor
b) HTabDescriptor
c) HColumnDescriptor
d) All of the mentioned
View Answer

Answer: c
Explanation: The minimum number of row versions parameter is used together with the time-to-live parameter and can be combined with the number of row versions parameter.

2. Point out the correct statement.
a) The default for max versions is 1
b) It is recommended setting the number of max versions to an exceedingly high level
c) HBase does overwrite row values
d) All of the mentioned
View Answer

Answer: a
Explanation: The number of max versions may need to be increased or decreased depending on application needs.

3. HBase supports a ____________ interface via Put and Result.
a) “bytes-in/bytes-out”
b) “bytes-in”
c) “bytes-out”
d) none of the mentioned
View Answer

Answer: a
Explanation: Input could be strings, numbers, complex objects, or even images as long as they can rendered as bytes.

4. One supported data type that deserves special mention are ____________
a) money
b) counters
c) smallint
d) tinyint
View Answer

Answer: b
Explanation: Synchronization on counters are done on the RegionServer, not in the client.

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5. Point out the wrong statement.
a) Where time-ranges are very wide (e.g., year-long report) and where the data is voluminous, summary tables are a common approach
b) Coprocessors act like RDBMS triggers
c) HBase does not currently support ‘constraints’ in traditional (SQL) database parlance
d) None of the mentioned
View Answer

Answer: c
Explanation: The advised usage for Constraints is in enforcing business rules for attributes in the table.

6. The _________ suffers from the monotonically increasing rowkey problem.
a) rowkey
b) columnkey
c) counterkey
d) all of the mentioned
View Answer

Answer: a
Explanation: Attention must be paid to the number of buckets because this will require the same number of scans to return results.

7. __________ does re-write data and pack rows into columns for certain time-periods.
a) OpenTS
b) OpenTSDB
c) OpenTSD
d) OpenDB
View Answer

Answer: b
Explanation: OpenTSDB is a very advanced processing technique.

8. Which command is used to disable all the tables matching the given regex?
a) remove all
b) drop all
c) disable_all
d) all of the mentioned
View Answer

Answer: c
Explanation: The syntax for disable_all command is as follows : hbase> disable_all ‘r.*’

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9. __________ command disables drops and recreates a table.
a) drop
b) truncate
c) delete
d) none of the mentioned
View Answer

Answer: b
Explanation: The syntax of truncate is as follows: hbase> truncate ‘table name’.

10. Correct and valid syntax for count command is ____________
a) count ‘<row number>’
b) count ‘<table name>’
c) count ‘<column name>’
d) none of the mentioned
View Answer

Answer: b
Explanation: You can count the number of rows of a table using the count command.

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Sanfoundry Global Education & Learning Series – Hadoop.

Here’s the list of Best Books in Hadoop.

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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