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

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


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Explanation: CQL shell commands that import and export CSV (comma-separated values or delimited text files).

COPY TO exports data from a table into a CSV file. Each row is written to a line in the target file with fields separated by
the delimiter. All fields are exported when no column names are specified. To drop columns, specify a column list.
COPY FROM imports data from a CSV file into an existing table. Each line in the source file is imported as a row. All rows in
the dataset must contain the same number of fields and have values in the PRIMARY KEY fields. The process verifies the PRIMARY
KEY and updates existing records. If HEADER = false and no column names are specified, the fields are imported in
deterministic order. When column names are specified, fields are imported in that order. Missing and empty fields are set to
null. The source cannot have more fields than the target table, however it can have fewer fields.





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

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Explanation: Keyspaces
A cluster is a container for keyspacesa"typically a single keyspace. A keyspace is the
outermost container for data in Cassandra, corresponding closely to a relational database.
Like a relational database, a keyspace has a name and a set of attributes that define
keyspace-wide behavior. Although people frequently advise that itas a good idea to
create a single keyspace per application, this doesnat appear to have much practical
basis. Itas certainly an acceptable practice, but itas perfectly fine to create as many keyspaces
as your application needs. Note, however, that you will probably run into trouble
creating thousands of keyspaces per application.
Depending on your security constraints and partitioner, itas fine to run multiple keyspaces
on the same cluster. For example, if your application is called Twitter, you
would probably have a cluster called Twitter-Cluster and a keyspace called Twitter.
To my knowledge, there are currently no naming conventions in Cassandra for such
items.
In Cassandra, the basic attributes that you can set per keyspace are:
Replication factor
In simplest terms, the replication factor refers to the number of nodes that will act
as copies (replicas) of each row of data. If your replication factor is 3, then three
nodes in the ring will have copies of each row, and this replication is transparent
to clients.
The replication factor essentially allows you to decide how much you want to pay
in performance to gain more consistency. That is, your consistency level for reading
and writing data is based on the replication factor.
Replica placement strategy
The replica placement refers to how the replicas will be placed in the ring. There
are different strategies that ship with Cassandra for determining which nodes
will get copies of which keys. These are SimpleStrategy (formerly known as
RackUnawareStrategy), OldNetworkTopologyStrategy (formerly known as Rack-
AwareStrategy), and NetworkTopologyStrategy (formerly known as Datacenter-
ShardStrategy).
Column families
In the same way that a database is a container for tables, a keyspace is a container
for a list of one or more column families. A column family is roughly analagous to
a table in the relational model, and is a container for a collection of rows. Each row
contains ordered columns. Column families represent the structure of your data.
Each keyspace has at least one and often many column families.





Question : Keyspace contains tables?

1. True
2. False

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Explanation:

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