Question-106: How do you define the replication factor?

Answer: For ensuring the fault tolerance, in Cassandra cluster. Same data is copied on multiple nodes. And data should be copied on how many numbers of nodes is driven by the replication factor. Suppose the replication factor is 3 then Same data is copied over three nodes in the cluster, and three copies of the same data is maintained.

Question-107: What all possible type of NoSQL database available?

Answer: There are following types of NoSQL databases are available

• Document store database like mongo DB 
• Key value Store for example HBase
• Columnar type of database
• Graph database

Question-108: What is the basic feature of NoSQL database?

Answer: NoSQL database is are generally

• Does not have a strong schema define
• They are generally scalable, just by adding a node it should automatically get scaled.
• Data is distributed across multiple nodes in the cluster.
• It could have an inbuilt caching mechanism for faster read of the data
• It would have tunable consistency.
• Usually transactions are not supported some database has lite weight transaction like Cassandra database.

Question-109: Why should I use the Cassandra database?

Answer: Cassandra database has many advantages over any other available NoSQL database or with respect to RDBMS it is also quite different for example

• Data is replicated across various nodes so it is considered highly fault tolerant database.
• It can store terabytes of data
• It is linearly scalable database
• Cluster can span across multiple geography for example having multiple datacenters.
• Even you can maintain the consistency on a datacenter level.

Question-110: What programming language is used to develop a Cassandra database?

Answer: Cassandra database was developed using the Java programming language hence, GC tuning is very critical for the Cassandra database.