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

Question : Which is or are true for Major Compaction
1. Can be configured with hbase.hregion.majorcompaction
2. Heavyweight operation - run when load is low
3. Access Mostly Uused Products by 50000+ Subscribers
4. MemStore can flush to disk during compaction



1. 1,2 and 3
2. 1 and 2
3. Access Mostly Uused Products by 50000+ Subscribers
4. 1 and 3
5. 1 and 4


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Major Compaction
- Reads all the Store files and writes to a single Store
- Deleted rows and expired versions are removed
- Happens once daily
- Can be configured with hbase.hregion.majorcompaction
- Heavyweight operation - run when load is low




Question : Minor Compaction ....

1. Can be configured with hbase.hstore.compactionThreshold
2. Larger number of compactions will take longer but will be fewer
3. Access Mostly Uused Products by 50000+ Subscribers
4. All 1,2 and 3 are correct



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Minor Compaction
- Combines some Store files into a single file
- Runs after three Store files have accumulated
- Can be configured with hbase.hstore.compactionThreshold
- Larger number of compactions will take longer but will be fewer
- MemStore cannot flush to disk during compaction
- If MemStore runs out of memory, clients will hang or timeout





Question : HLog is an WAL (Write Ahead Log ) implementation

1. True
2. False


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Related Questions

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Question :

Your client application needs to scan a region for a row key value 104. Given a store that contains the following list of RowKey values

100,101,102,103,104,105,106,107

A bloomfilter return which of the following



1. Confirmation that 104 may be contained in the set
2. Confirmation that 104 is contained in the set
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4. The file offset of the value 104





Question : You want to do a full table scan on your data. You decide to disable block caching to see if this improves scan performance.
Will disabling block caching improve scan performance. Will disabling block caching improve scan performance ?

1. No, disabling blcok caching does not improve scan performance.
2. Yes, when you disable blcok caching, you free up that memory for the other operations. With a full table scan, you can not take
take advantage of block caching anyway because your entire table would not fit into cache.
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4. Yes, when you disable block caching, you free up memory for MemStore, which improves, scan performance.





Question : Your organization has an HBase cluster with half the nodes in Geneva and half the nodes in Neveda. Which of the following is true?

1. There must be two NameNodes one for Geneva and another for Neveda
2. As they are very far to each other avoid replication of the data and set replication factor=1

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4. Keep one datacenter as a backup and do not load any data in that.



Question : You have a AcmeLog table in HBase. The RowKeys are numbers.
You want to retrieve all entries that have row key 100.
Which shell command should you use?

1. get 'AcmeLog', (FILTER ='100')
2. get 'AcmeLog', '100'

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4. scan 'AcmeLog', '100'




Question : You have a AcmeUsers table in HBase and you would like to insert a row that consists
of a AcmeID,jayesh2014 and an email address, john@acmeshell.com. The table has a single Column Family
named Meta and the row key will be the Acme's ID. Which command help in this case?

1. put 'AcmeUsers', 'jayesh2014', 'john@acmeshell.com'

2. put 'AcmeUsers', 'Meta:AcmeID', 'jayesh2014', 'Email, 'john@acmeshell.com'

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4. put 'AcmeUsers', 'AcmeID:jayesh2014', 'Email:john@acmeshell.com'




Question : You are storing page view data for a large number of Web sites, each of which has
many subdomains (www.acmeshell.com, archive.acmeshell.com, beta.acmeshell.com, etc.). Your reporting tool needs
to retrieve the total number of page views for a given subdomain of a Web site. Which of the following rowkeys should you use?

1. The domain name followed by the URL

2. The URL followed by the reverse domain name

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4. The URL