DataStax Cassandra Developer Certification Certification Questions and Answer (Dumps and Practice Questions)
Question : You have been given below conceptual data model for HadoopExam Inc online training institute.
Please find the correct query for given access pattern
where author_name = ? (All the courses created by an author)
1. A
2. B
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4. D
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Explanation: as we know this is a 1 to many relationship. Now criteria for access pattern in author_name. However,
to uniquely identify a row, we should have a course_id as well included.
Here, we have not added email column as a static column. Because, if we added email as a static column then single partition
(author name = “Amit Jain" could not be uniue, which is partition key). And we know static columns are stored per partition.
Assume we have multiple author with the same name “Amit Jain" and all author will fall in same partition, now static column
(email, if we have decalred it as static) will be stored only once and as soon as you update email id it will be upsert and
causes email id to be updated for all the author with same name.
Question : You have been given below conceptual data model for HadoopExam Inc online training institute.
Please find the correct query for given access pattern
where user_id = ? and video_id=? (All the comments by a user)
1. A
2. B
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4. D
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Explanation: It’s many to many relationship, also we have equality access pattern so user_id and course_id will
be partition key. To uniquely identify many to many relationship, we have to use both entity key as well as relationship key.
Regarding static column : Yes, we can have user_emai, course_name and description as a static column. They are stored once for
each partition, and here for user_id and course_id is unique for each row, so we can have these columns as static key.
Question : . You have been given below conceptual data model for HadoopExam Inc online training institute.
Please find the correct query for given access pattern
where user_id = ? and comment_date>? (All the comments by a user)
1. A
2. B
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4. D
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Explanation: : It’s many to many relationship, also we have equality access pattern so user_id will be partition
key. To uniquely identify many to many relationship, we have to use both entity key as well as relationship key. However, here
we have inequality operator as well, which causes this to be part of clustering key (commnet_date).
Regarding static column: Yes, we can have user_email, as a static column. It is stored once for each partition, and here for
user_id is unique for each row, so we can have these columns as static key.
Related Questions
Question : You have been given a Cassandra cluster (Ring) with nodes, and new KeySpace created by Admin named AcmeKeySpace
and you want to insert configuration data for your mobile application
named AcmeApp. And administrator had told you that default Replication Factor is 3 on this cluster for your AcmeKeySpace. Now
you have inserted 50 records in a table of your AcmeKeySpace.
Select correct statement which apply.
1. After insert query, you have to execute another command named 'replicate-all', using cqlsh. So data can be
replicated on three nodes.
2. Before insert query, you have to execute another command named 'replicate-all', using cqlsh, for the
session. So data can be replicated on three nodes.
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4. Either of 1 and 2
Question : Which is true about replication factor having value more than
1. Single node token range will be having more spread.
2. Overall storage capacity for different data will be reduced
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4. 1 and 2
5. 1,2 and 3
Question : You are working as a Database Architect for Arinika Inc. You have been given a project where expected data volume
is quite high, approximately 3TB in a month. For that you have to do data modeling, so which three layers come in your mind
while doing data modeling?
1. Workflow, Logical, Physical
2. Conceptual, Logical, Physical
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4. Physical, Logical, Conceptual
Question : You are working with a financial indexing data company, who had recently acquired a real estate company. This
real estate Data Company is storing their data in excel and they never had a RDBMS in their organization. You already have
Cassandra in your company and you want to put this data which is in excel as a csv or pipe separated. Which of the following
command will help you to bring this data in Cassandra?
1. COPY
2. COPY FORM
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4. REPLICATE
Question : Which all are correct, with regards to defining Cassandra Keyspace?
1. Top-level namespace/container
2. Similar to a relational database schema
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4. 1,2
5. 1,2,3
Question : Keyspace contains tables?
1. True
2. False