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

Question : In which of the following scenario indexes should be avoided?

A. On high-cardinality columns
B. In tables that use a counter column
C. On a frequently updated or deleted column.
D. To look for a row in a large partition unless narrowly queried


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

Correct Answer : Get Lastest Questions and Answer :
Explanation: Do not use an index in these situations:
On high-cardinality columns because you then query a huge volume of records for a small number of results.
In tables that use a counter column
On a frequently updated or deleted column.
To look for a row in a large partition unless narrowly queried.





Question : You have a Books database with following columns

BOOK_TITEL
BOOK_AUTHOR
BOOK_PRIMARY_KEYWORD

Assume, each book is written by individual author and one author has written only one book. Its possible that primary keyword
can be shared among various books. There are almost 10M books in this table. Which of the following is correct with regards to
index?

1. You can create index on both BOOK_AUTHOR and BOOK_PRIMARY_KEYWORD

2. You can create index on BOOK_AUTHOR and avoid on BOOK_PRIMARY_KEYWORD

3. Access Mostly Uused Products by 50000+ Subscribers

4. On millions record table, we should not have index any columns.


Correct Answer : Get Lastest Questions and Answer :
Explanation: If you create an index on a high-cardinality column, which has many distinct values, a query between
the fields will incur many seeks for very few results. In the table with a million books, looking up books by author a value
that is unique for each book instead of by their keyword, is likely to be very inefficient.




Question : You must always create index to frequently updated or deleted column

1. True
2. False

Correct Answer : Get Lastest Questions and Answer :
Explanation: : Cassandra stores tombstones in the index until the tombstone limit reaches 100K cells. After
exceeding the tombstone limit, the query that uses the indexed value will fail.

Related Questions

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Question : Please map the bwlow.
A. Murmur3Partitioner
B. RandomPartitioner
C. ByteOrderedPartitioner

1. Provides fast hashing and good performance
2. Uniformly distributes data across the cluster based on MD5 hash values
3. Partitioner for ordered partitioning


1. A-3 B-2 C-1

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


Question : Both RandomPartitioner and MurmurPartitioner uses a cryptographic hash to generates the token hash values



1. True
2. False


Question : You are designing Cassandra cluster, and you have been asked to span cluster in Geneva,
Nevada and Hyderabad. Which of the following replication strategies you will use for this.


1. SimpleStrategy

2. NetworkTopologyStrategy

3. Murmur3Strategy

4. RandomStrategy



Question : You are designing Cassandra cluster, and you have been asked to span cluster in Geneva, Nevada and Hyderabad.
You can configure consistency level of LOCAL_QUORUM or ONE.
The two primary considerations are
(1) being able to satisfy reads locally, without incurring cross data-center latency, and
(2) failure scenarios :
Which is the best strategy to configure replications.

1. Two replicas in each data center e.g. 2 copy in each DC Geneva, Nevada and Hyderabad
2. Three replicas in each data center e.g. 2 copy in each DC Geneva, Nevada and Hyderabad
3. One replica in each data center e.g. 1 copy in each DC Geneva, Nevada and Hyderabad
4. You can have three replicas in one data center e.g. Geneva and single replica in either Nevada and
Hyderabad


Question : Replication strategy is set during



1. Keyspace creation

2. Cluster creation

3. Table Creation

4. ColumnFamily Creation



Question : Which of the following components of Cassandra help you to determine which data centers and racks nodes belong
to.


1. Network topology

2. Replication Strategy

3. Snitch

4. Partitioner