Premium

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



Question : You have setup of virtual node (vnode) to avoid HotSpot issue in Cassandra cluster, what will be the correct in
this case

A. You donat need to add new node in the cluster
B. As soon as you add new node in cluster, it's going to be able to take ranges of data from every node
C. It will re-partition all the data after adding new node
D. You can assign token more efficiently to each node in cluster

: You have setup of virtual node (vnode) to avoid HotSpot issue in Cassandra cluster, what will be the correct in
1. A,B
2. B,C
3. C,D
4. A,D
5. B,D

Correct Answer : Get Lastest Questions and Answer :
Explanation: When you add new node to the Cluster, it will take ranges of data from every node, so this is a much
more even way to get that data. It is going to re-partition data. and all the other nodes will give some data to be loaded in
new node and that node is able to come online faster, and also gives us the ability to add a single node to a lopsided cluster
or one at a time, which is a lot easier as an operator to make work. If you have to assign tokens and make up the tokens, that
can be a lot more work, and sometimes you don't get it right. With virtual nodes, it's much easier.

Within a cluster, virtual nodes are randomly selected and non-contiguous. The placement of a row is determined by the hash of
the partition key within many smaller partition ranges belonging to each node.





Question : You do configuration in Cassandra.yaml file to setup number of tokens in your cluster.
: You do configuration in Cassandra.yaml file to setup number of tokens in your cluster.
1. True
2. False

Correct Answer : Get Lastest Questions and Answer :
Explanation: We have a Cassandra yaml setting for how many tokens you want to set up.
Set the number of tokens on each node in your cluster with the num_tokens parameter in the cassandra.yaml file.





Question : You already have an existing Cassandra cluster setup, having single token node setup. How, would you convert this
setup to vnode setup?

: You already have an existing Cassandra cluster setup, having single token node setup. How, would you convert this
1. It cannot be done, you have to create new Cluster altogether

2. you can configure another datacenter configured with vnodes already enabled and let Cassandra automatic
mechanisms distribute the existing data into the new nodes.

3. you can configure another Cassandra cluster configured with vnodes already enabled and let Cassandra
automatic mechanisms distribute the existing data into the new Cluster.

4. 2 and 3

Correct Answer : Get Lastest Questions and Answer :
Explanation: You cannot directly convert a single-token nodes to a vnode. However, you can configure another
datacenter configured with vnodes already enabled and let Cassandra automatic mechanisms distribute the existing data into the
new nodes. This method has the least impact on performance.

Procedure

Add a new datacenter to the cluster.
Once the new datacenter with vnodes enabled is up, switch your clients to use the new datacenter.
Run a full repair with nodetool repair.
This step ensures that after you move the client to the new datacenter that any previous writes are added to the new
datacenter and that nothing else, such as hints, is dropped when you remove the old datacenter.

Update your schema to no longer reference the old datacenter.
Remove the old datacenter from the cluster.



Related Questions

Question : You have defined a table as below

CREATE TABLE TRINING_COURSE (
id uuid,
course_sequence int,
course_id uuid,
title text,
category text,
trainer text,
PRIMARY KEY (id, course_sequence ) );

ALTER TABLE TRINING_COURSE ADD LOCATION map;

Which of the following is correct CQL to add new location for a training_course ?
 : You have defined a table as below
1. INSERT INTO TRINING_COURSE (id, course_sequence, LOCATION)
VALUES (62c36092-82a1-3a00-93d1-46196ee77204, 4,
{ '2017-9-22 09:00' : 'MUMBAI',
'2017-10-1 09:00' : 'CHENNAI'});


2. UPDATE TRINING_COURSE SET LOCATION = LOCATION + {'2017-9-22 09:00' : 'MUMBAI'}
WHERE id = 62c36092-82a1-3a00-93d1-46196ee77204 AND course_sequence = 4;


3. Access Mostly Uused Products by 50000+ Subscribers
WHERE id = 62c36092-82a1-3a00-93d1-46196ee77204 AND course_sequence = 4;


4. UPDATE TRINING_COURSE ADD {LOCATION + {'2017-9-22 09:00' : 'MUMBAI'}}
WHERE id = 62c36092-82a1-3a00-93d1-46196ee77204 AND course_sequence = 4;



Question : You have following table definition

CREATE TABLE TRINING_COURSE (
id uuid,
course_sequence int,
course_id uuid,
title text,
category text,
trainer text,
PRIMARY KEY (id, course_sequence ) );

ALTER TABLE TRINING_COURSE ADD LOCATION map;
ALTER TABLE TRINING_COURSE ADD emails set;

Which of the following will be a correct syntax ?
 : You have following table definition
1. CREATE INDEX EMAIL_INDEX ON TRINING_COURSE (emails);

2. CREATE INDEX ON TRINING_COURSE (emails);

 3. Access Mostly Uused Products by 50000+ Subscribers

4. 1 and 2

5. 1,2 and 3



Question : You have following table definition

CREATE TABLE TRINING_COURSE (
id uuid,
course_sequence int,
course_id uuid,
title text,
category text,
trainer text,
PRIMARY KEY (id, course_sequence ) );

ALTER TABLE TRINING_COURSE ADD LOCATION map;
ALTER TABLE TRINING_COURSE ADD emails set;

And you also apply the following CQL

CREATE INDEX ON TRINING_COURSE (LOCATION);

Which of the following statement is correct with regards to above query ?
 : You have following table definition
1. It will create an index on LOCATION maps values part

2. It will create an index on LOCATION maps Keys part

 3. Access Mostly Uused Products by 50000+ Subscribers

4. This command will fail



Question : You have following table definition

CREATE TABLE TRINING_COURSE (
id uuid,
course_sequence int,
course_id uuid,
title text,
category text,
trainer text,
PRIMARY KEY (id, course_sequence ) );

ALTER TABLE TRINING_COURSE ADD LOCATION map;
ALTER TABLE TRINING_COURSE ADD emails set;

And you also apply the following CQL

CREATE INDEX MYINDEXVALUE ON TRINING_COURSE (LOCATION);
CREATE INDEX MYINDEXKEY ON TRINING_COURSE (KEYS(LOCATION));

Which statement is correct ?
: You have following table definition
1. There will be two indexes created one on Location keys and other on Location values

2. There will be only one index created on Location keys and other will be auto dropped on Location values

 3. Access Mostly Uused Products by 50000+ Subscribers

4. When you try to create index on Location keys, it will give error.



Question : You have following table definition

CREATE TABLE TRINING_COURSE (
id uuid,
course_sequence int,
course_id uuid,
title text,
category text,
trainer text,
PRIMARY KEY (id, course_sequence ) );

ALTER TABLE TRINING_COURSE ADD emails set;

Now, you need to select all rows having email id as 'admin@hadoopexam.com' , which of the following are correct syntax ?
 : You have following table definition
1. SELECT * FROM TRINING_COURSE WHERE emails CONTAINS 'admin@hadoopexam.com' ;

2. SELECT * FROM TRINING_COURSE WHERE emails HAVING 'admin@hadoopexam.com' ;

 3. Access Mostly Uused Products by 50000+ Subscribers

4. SELECT * FROM TRINING_COURSE WHERE emails IN ('admin@hadoopexam.com' );



Question : You have following table definition

CREATE TABLE TRINING_COURSE (
id uuid,
course_sequence int,
course_id uuid,
title text,
category text,
trainer text,
PRIMARY KEY (id, course_sequence ) );

CREATE INDEX MYINDEXVALUE ON TRINING_COURSE (LOCATION);

Now, you need to select all rows having TRAINING_COURSE ORGANIZED IN a˜Mumbaia which of the following are correct syntax ?
 : You have following table definition
1. SELECT * FROM TRINING_COURSE WHERE LOCATION CONTAINS 'MUMBAI';

2. SELECT * FROM TRINING_COURSE WHERE LOCATION IN { 'MUMBAI' };

 3. Access Mostly Uused Products by 50000+ Subscribers

4. SELECT * FROM TRINING_COURSE WHERE LOCATION HAVING 'MUMBAI';