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

Question : You have been given below ER Diagram

What is the correct table design to satisfy below query?

Query: Find all author that matches specific category and also show the most recently published first

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

Correct Answer : Get Lastest Questions and Answer :
Explanation: look at the query first

"Find all author that matches specific category and also show the most recently published first"

Consider Mapping rules

Entities and relationships -> Author and Book
equality search attributes -> Category
inequiality search attributes -> Not applicable
ordering attributes -> publish_date
key attributes -> book_id

. We are querying based on category, hence category must be in primary key.
. Most recently published first , hence order by on publish_date order by descending
. We need to make PK unique, hence we will as book_id in PK (It is 1 to many relationship, hence we will take key from many
side, one author can write many books. Book_id will be unique in this relation.
. Rest of the attributes from both the relation.

Question : Which one would you prefer , when data duplication is done because of schema design ?

1. Constant duplication

2. Exponential duplication

3. Access Mostly Uused Products by 50000+ Subscribers

4. 1 and 2

4. 1 and 3

Correct Answer : Get Lastest Questions and Answer :
Explanation: : Constant duplication is fine. You must not have exponential and non-constant data duplication, it
can cause your database storage filled faster and you
will be out of space.

Question : You have been given below ER Diagram

What is the correct table design to satisfy below query?

Query: Find all books that is subscribed by a subscriber and support writing year range, with most writing year first then
sorted by title.

1. A
2. B
3. Access Mostly Uused Products by 50000+ Subscribers
4. D

Correct Answer : Get Lastest Questions and Answer :
Explanation: Please check query first

Find all books that is subscribed by a subscriber and support writing year range, with most writing year first then sorted by
title.

Consider Mapping Rules

Entities and relationships -> e-Book and e-Subscriber
equality search attributes -> subscriber_id
inequiality search attributes -> writing_year
ordering attributes -> writing_year, title
key attributes -> book_id,subscriber_id, subscription_date (because in m to m relationship, we take keys from both the enity as
well as from relationship)

Related Questions

Question : Cassandra database tables always be in rd normal form?

1. True
2. False

Question : You have been given below structure of data, with Cassandra datatypes

course_id timeuuid
published_date timestamp
category set
title text
trainer text

Following are the table structure

CREATE TABLE HadoopExam (
course_id timeuuid,
published_date timestamp,
category set,
title text,
trainer text
PRIMARY KEY ( XXXX )
) WITH CLUSTERING ORDER BY ( YYYYY);

Now replace the correct value of XXXX and YYYY, to satisfy the below requirement

Retrieve course a trainer has created in (newest first).

1. XXXX=((trainer), published_date, course_id) and YYYY= published_date DESC ,course_id ASC

2. XXXX=((course_id), published_date, trainer) and YYYY= trainer DESC ,course_id ASC

3. Access Mostly Uused Products by 50000+ Subscribers

4. XXXX=((course_id), published_date, trainer) and YYYY= published_date DESC ,course_id DESC

5.

Question : You have been given below table definition

CREATE TABLE books_by_category (
category text,
published_date timestamp,
book_id timeuuid,
title text,
PRIMARY KEY ( XXXX)
) WITH CLUSTERING ORDER BY (YYYY );

Now fill in the values in XXXX and YYYY , which satisfies the below query requirement

Retrieve books within a particular category (newest fist).

1. XXXX= ((category), book_id, published_date ) and YYYY=published_date DESC , book_id ASC

2. XXXX= ((category), published_date, book_id) and YYYY=published_date DESC , book_id ASC

3. Access Mostly Uused Products by 50000+ Subscribers

4. XXXX= ((category), published_date ) and YYYY=published_date DESC

Question : You have been given a relationship diagram, with to relationship.

E.g. there are two entity Person and Passport

Each person can have only one passport and each passport can belong to one person.

Person : Person_ID (Unique in database)
Passport : Passport Number (Unique in database)

So, which would be the correct keys in this case?

1. Key attributes of either participating entity types
2. Key attributes of both participating entity types
3. Access Mostly Uused Products by 50000+ Subscribers
4. Key attribute of the relationship type

Question : . You are uploading your video on HadoopExam training website HadoopExam.com , and you have following
relationship. One user id can upload many videos. However, each video has a unique id. So in this case how do you find unique
key for 1 to n relationship?

1. Key attributes of either participating entity types

2. Key attributes of both participating entity types

3. Access Mostly Uused Products by 50000+ Subscribers

4. Key attribute of the relationship type

Question : You have been writing a technical book, which will be published on HadoopExam website. Now, HadoopExam had
provided many other authors to help you complete your book on time. Hence, we are having here many to many relationship. One
book can be written by multiple author and an author can write multiple books. Now, you need to find unique relation, how
would you find in this case.

You will be having unique author_id and unique book_id

Author(Author_id) -----(m to m) ------ Book (BookId)

1. Key attributes of either participating entity types

2. Key attributes of both participating entity types

3. Access Mostly Uused Products by 50000+ Subscribers

4. Key attribute of the relationship type