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 – performance is better than traditional sql
- Schema free – Dynamic 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:
- Key value store
- Column
- Document Oriented
- Graph store
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