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

Question : Which of the following is correct for collections in Cassandra table ?

1. Use collections when you want to denormalize a small amount of data.

2. Use collections when you want to store a small amount of data.

3. Access Mostly Uused Products by 50000+ Subscribers

4. 1 and 2

5. 1,2 and 3


Correct Answer : Get Lastest Questions and Answer :
Explanation: Use collections when you want to store or denormalize a small amount of data. Values of items in
collections are limited to 64K. Other limitations also apply. Collections work well for storing data such as the phone numbers
of a user and labels applied to an email. If the data you need to store has unbounded growth potential, such as all the
messages sent by a user or events registered by a sensor, do not use collections. Instead, use a table having a compound
primary key and store data in the clustering columns.




Question : Which of the following statement true, with regards to Cassandra Index?


1. An index provides a means to access data in Cassandra using attributes other than the partition key.

2. You can index collection columns

3. Access Mostly Uused Products by 50000+ Subscribers

4. 1 and 2

5. 1 and 3


Correct Answer : Get Lastest Questions and Answer :
Explanation: An index provides a means to access data in Cassandra using attributes other than the partition key.
The benefit is fast, efficient lookup of data matching a given condition. The index indexes column values in a separate,
hidden table from the one that contains the values being indexed. Cassandra has a number of techniques for guarding against
the undesirable scenario where a data might be incorrectly retrieved during a query involving indexes on the basis of stale
values in the index.

As mentioned earlier, in Cassandra 2.1 and later, you can index collection columns.





Question : The more unique values that exist in a particular column, the more overhead you will have, on average, to query
and maintain the index.

1. True
2. False

Correct Answer : Get Lastest Questions and Answer :
Explanation: The more unique values that exist in a particular column, the more overhead you will have, on
average, to query and maintain the index. For example, suppose you had a books table with a billion books and wanted to look
up book by the author. Many books will share the same column value for author. The author column is a good candidate for an
index.

Related Questions

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Question : Map the below, components
A. Node
B. Data center
C. Cluster

1. It can span Physical locations
2. Where you store your data. It is the basic infrastructure component of Cassandra
3. A collection of related machines and can be physical as well as virtual


1. A-2 , B-3 , C-1

2. A-1 , B-2 , C-3
3. A-1 , B-3 , C-2
4. A-3 , B-1 , C-2


Question : Map the followings
A. Commit log
B. SSTable
C. CQL Table

1. Consists of columns and has a primary key
2. All data is written first to this for durability.
3. Maintained for each Cassandra table


1. A-1 B-2 C-3

2. A-3 B-2 C-1
3. A-1 B-3 C-2
4. A-2 B-3 C-1


Question : Select correct statements, with regards to Gossip protocol.
A. Using Gossip protocol nodes periodically exchange state information about themselves and about other nodes they know about.
B. The gossip process runs every 5 seconds and exchanges state messages with as many other nodes in the cluster as possible.
C. The nodes exchange information about themselves and about the other nodes that they have gossiped about,
so all nodes quickly learn about all other nodes in the cluster.
D. A gossip message has a version associated with it


1. A,B,C
2. B,C,D
3. A,C,D
4. A,B,C,D


Question : Select all correct statements which applies to seed nodes
A. Use the multiple list of seed nodes in a cluster, so all nodes quickly learn about all other nodes in the cluster
B. The seed node designation has no purpose other than bootstrapping the gossip process for new nodes joining the cluster
C. Seed nodes are not a single point of failure
D. Seed nodes are a single point of failure


1. A,B
2. B,C
3. C,D
4. A,D
5. B,D


Question : Select all correct statements which applies to seed nodes
A. In multiple data-center clusters, the seed list should include at least one node from each data center (replication group).
B. More than a single seed node per data center is recommended for fault tolerance
C. Making every node a seed node is recommended for fault tolerance
D. It is recommended to use a small seed list (approximately three nodes per data center).


1. A,B,C
2. B,C,D
3. A,C,D
4. A,B,D


Question : In Cassandra database, which of the following help us to put new row on a particular node in a cluster.



1. Hashing

2. Partitioner

3. Gossip protocol

4. Grouping

5. Timestamps