No-SQL databases

Establishing relationships between data in SQL databases comes at a cost of performance of the database server. When it used a lot, then usually scaling up, or getting better hardware is usually the only available option.

To overcome this limitation NoSQL databases were invented. NoSQL databases do not track data dependencies. This work is done by the application. Because of lower overhead of the database server, these databases are faster than SQL databases.

Relationship of the data is ensured by an application rather than database server. When database is busy, then it is possible to scale horizontally. Scaling horizontally means getting more hardware.

There are two main reasons of scaling horizontally vs. scaling vertically.

  1. Horizontal scalability is a better option than vertical scalability. It is possible to add more servers rather than getting a faster one.
  2. Horizontal scalability cost less than vertical scalability. In vertical scalability it is necessary to get a faster machine. It means spending a lot of money. In horizontal scalability it is possible to get more machines. Each machine will cost less than a new server in vertical scalability. In horizontal scalability, new machines need not to match performance of existing hardware.

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