CassandraHadoopMongoDB

NoSQL and Advantages of NOSQL

Why NoSQL?

 – Bigger data handling capability  

  • To handle Volume of data it allows data to be spread across commodity hardware

 – Elastic scaling  

  • Scale out the storage

 – Flexible Schema/fixed data model 

  •   It does not need a organized schema. The schema is dynamic or fixed schema

 – Integrated caching facility

  •   To Increase performance, NOSQL cache data in system memory

 – Data complexity  

  • Data is stored and managed in different data center

Advantages of NOSQL? 

  • Distributed architecture – Easy to scale out storage
  • First reads : write once and read multiple times
  • Easy replication – handle failover solution
  • Higher performance – performanace is better than traditional sql
  • Schema free – Dynamic and and flexible schema
  • Fast development – In NOSQL, we don’t have JOINS and No ACID transactions

CAP Theorem for a distributed architecture:

Consistency: The data in database remains consistent after the execution of an operation.Example: After an insert operation all clients will see the same data

Availability:The System is always On/Available.

Partition Tolerance:The system continues to function even if the servers are not able to communicate with each other

CAP provides the basic requirement to follow 2 of the 3 requirements in distributed system. it is impossible to follow all 3 requirements, so NOSQL DB follows different combination of C,A,P from CAP theorem.

CA: Single site cluster , all nodes are always in contact. when partition occurs system blocks.

CP: some data may not be available but the rest is still consistent and accurate

AP: System is still available under partitioning but some of the data may be inaccurate.

Types of NOSQL Database:

  • Keyvalue store
  • Column
  • Document Oriented
  • Graph store

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