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

Question : You have been given metadata for creating Cassandra table.

Category text
Created_year int
course_id uuid
published_date timestamp
course_detail text
course_title text
user_id uuid

And you have created table as below

CREATE TABLE HADOOPEXAM (
Category text,
Created_year int,
published_date timestamp,
course_title text,
course_detail text,
user_id uuid,
course_id uuid,
PRIMARY KEY ((course_id))
);

What do you see in above table creation definition assuming combination of these three columns course_id,Category,Created_year
to be unique across all data.


1. It is a good design of table, it can avoid the upserts.

2. It is a good design of table, and you can easily do the range query on Created_year column.

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4. Its not a good or bad design. Itas based on requirement.


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Explanation: Certainly its a bad table design in Cassandra. As you know it will not take care of record uniqueness
also you can not make range query based on Created_year column.

Assume our data as below

course_id,published_date,Created_year,course_title,course_detail,user_id
1, 15-Aug-2017,2017,Cassandra,ONLINE,xyz
1, 15-Aug-2017,2017,Cassandra,OFFLINE,xyz
1, 15-Aug-2017,2017,Cassandra,CLASSROOM,xyz

In this case last rows will be kept in table, because it will apply the upserts and which is not good design.





Question : You have been given below metadata for creating Cassandra table.

Category text
Created_year int
course_id uuid
published_date timestamp
course_detail text
user_id uuid

In this assuming combination of these three columns course_id,Category,Created_year to be unique across all data.
Now you need to design a table where allow users to query on Category and possible created_year ranges while avoiding upserts
on import. You must also return your results in descending order of created_year.

1.



2.


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4.



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Explanation: As per the requirement, we should be able to query based on Category. Give me all the courses from a
particular Category.
We also want to support range query on a Created_year, hence there is certainly this column go for clustering.
Now as we know, our primary key column should be unique across all the data, hence we need to have course_id should be part of
primary key. Hence, correct table definition will be

CREATE TABLE HadoopExam (
Category text,
Created_year int,
course_id timeuuid,
published_date timestamp,
description text,
course_detail text,
user_id uuid,
PRIMARY KEY ( (Category), Created_year, course_id)
) WITH CLUSTERING ORDER BY (Created_year DESC );

This table will support following queries

SELECT * FROM HadoopExam where Category='BigData' and Created_year=2017;
SELECT * FROM HadoopExam where Category='BigData' and Created_year < 2017;

Below query will not be supported
SELECT * FROM HadoopExam where Created_year < 2017;





Question : You have wrongly loaded all the data in Cassandra table and want to delete all the rows from that table. Which of
the following will help you to do this?

1. DROP

2. TRUNCATE

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4. ERASE


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Explanation:

Related Questions

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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