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

Question : The purpose of clustering key is to store row data in sorted order.

1. True
2. False

Correct Answer : Get Lastest Questions and Answer :
Explanation: The purpose of clustering key is to store row data in sorted order. The sorting of data is based on
columns which are included in the clustering key. This arrangement makes it efficient to retrieve data using clustering key.




Question : You have been given below table definition

CREATE TABLE HADOOEXAM(

COURSE_TITLE text,
COURSE_ADDED_YEAR int,
COURSE_ADDED_DATE timestamp,
COURSE_DETAIL text,
USER_ID UUID,
COURSE_ID TIMEUUID,
PRIMARY KEY ((COURSE_TITLE,COURSE_ADDED_YEAR)));

What would be the result, when you run the below query?

SELECT * FROM HADOOEXAM WHERE COURSE_TITLE='CASSANDRA' ;

1. It will return all the courses which matches with the COURSE_TITLE='CASSANDRA'

2. It will return all the courses which is stored in the same partition where record for
COURSE_TITLE='CASSANDRA' stored

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4. This will say invalid query


Correct Answer : Get Lastest Questions and Answer :
Explanation: Yes, it will be invalid query. Because we have composite key. We need to add both the column from
primary key in where clause of the query.




Question : You have below tables defined with all the default Cassandra behavior. This table is empty
CREATE TABLE HADOOEXAM(

COURSE_TITLE text,
COURSE_ADDED_YEAR int,
COURSE_ADDED_DATE timestamp,
COURSE_DETAIL text,
USER_ID UUID,
COURSE_ID TIMEUUID,
PRIMARY KEY ((COURSE_TITLE)));

Now you fire the following query

UPDATE HADOOEXAM
SET COURSE_DETAIL ='HadoopExam Learning Resources'
WHERE COURSE_TITLE='CASSANRA' ;

What would happen?

1. It will throw error as there is no matching data

2. It will insert a new record

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4. None of the above


Correct Answer : Get Lastest Questions and Answer :
Explanation: Yes, it will insert a new record. As Cassandra default behavior does not do read before write. It
will do the given operations on table data. As it is not going to verify billions of record before inserting data.

Related Questions

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Question : It is not possible to "tune" Cassandra into a completely CA system.

1. True
2. False


Question : The consistency level determines the number of replicas that need to acknowledge the read or write operation
success to the client application.

1. True
2. False


Question : . Even at low consistency levels, Cassandra writes to all replicas of the partition key, including replicas in
other datacenters.

1. True
2. False


Question : What is linearizable consistency

1. Order of record updates does not matter, all the statement should be successful at the end of transaction.

2. Order of record updates matter, and should be executed in reverse order of that defined.

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4. None of this



Question : You have following consistency level configured, assume replication factor is

read operations using 2 out of 3 replicas to verify the value
write operations using 2 out of 3 replicas to verify the value

What is the overall consistency in this case?

1. Eventual

2. Light

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4. Initial



Question : Cassandra offers atomic, isolated, and durable transactions with eventual/tunable consistency

1. True
2. False