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DataStax Cassandra Developer Certification Certification Questions and Answer (Dumps and Practice Questions)



Question : You have been given below conceptual data model

And you have below Access pattern, which of the following is valid table design

where course_name=? and publish_date>?

: You have been given below conceptual data model
1. A
2. B
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4. D

Correct Answer : Get Lastest Questions and Answer :
Explanation: : In this case we know, both the course_name are equality operator. Hence, need to be part of primary
key and also publish_date is the part of inequality operator. Hence, it should be part of cluster key. Course_name is enough to
uniquely identify the course.




Question : You have data size is TB and your schema design will duplicate this data times, having replication factor=.
How much data are you going to duplicate?
: You have data size is TB and your schema design will duplicate this data times, having replication factor=.
1. 500TB

2. 50TB
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4. 5000TB


Correct Answer : Get Lastest Questions and Answer :
Explanation: As you have 10TB data size, , you will be duplicating entire data set. Hence, it will become 100TB,
now replication factor is 5. So total datasize will become = 500TB




Question : You have following table designed

Comment_By_course
comment_id K
course_id C
Title
description

For each comment_id, you will be copying entire course detail again. Is this an issue ?

: You have following table designed
1. Yes
2. No
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Correct Answer : Get Lastest Questions and Answer :
Explanation: Yes, this is an issue. Because as we know, there is no limit on number of comments a user can post. If
we copy entire course info for each comment, it will be a concern. Here, growth is multiple of number of comments and this is
not a constant value. If a user post 1000 comments, we will copy entire course info 5 times and that’s not at all good for
database growth.


Related Questions

Question : . In Cassandra insertions or updates of two or more rows in the same partition are treated as one write
operation.
: . In Cassandra insertions or updates of two or more rows in the same partition are treated as one write
1. True
2. False


Question : If you are using write consistency level of QUORUM with a replication factor of
: If you are using write consistency level of QUORUM with a replication factor of
1. Cassandra will replicate the write to all nodes in the cluster and wait for acknowledgement from two
nodes.

2. Cassandra will replicate the write to all nodes in the cluster and wait for acknowledgement from one of
the nodes.

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nodes.

4. Cassandra will replicate the write to all nodes in the cluster and does not wait for acknowledgement from
two nodes.



Question : Which of the following is true ?
 : Which of the following is true ?
1. Cassandra uses client-side timestamps to determine the most recent update to a column.

2. Cassandra uses server-side timestamps to determine the most recent update to a column.

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to a column.

4. Cassandra uses user provided timestamps to determine the most recent update to a column.



Question : Batch operation is isolated if it includes changes to more than one partition.
 : Batch operation is isolated if it includes changes to more than one partition.
1. True
2. False


Question : All writes to a replica node are recorded in which of the following before they are acknowledged as a success


 : All writes to a replica node are recorded in which of the following before they are acknowledged as a success
1. In Memory

2. commit log

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4. 1,2

5. 1,2 and 3


Question : In Cassandra data updates are performed as "compare (validation a condition) before setting (read before write)
" is known as

: In Cassandra data updates are performed as
1. Consistent Transaction

2. Eventual Consistent Transaction

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4. Durable Transaction