- This storage system stands for Not only SQL (structured query language).
- SQL queries cannot be used to access those databases.
- The goal is to fulfill the requirements of big data: scalability, availability and performance.
- More pragmatically, it allows to increase server storage increase (horizontal scalability) and maintenance of performance through a faster retrieval of the data.
- Again SQL cannot be used to query these databases. There are 4 types of non relational or No-SQL databases (It can be seen as a structured method for accessing what is being searched):
- key-value: for a given term there is a number or associations (value) which can contain multiple amounts of data.
- graph (popular with social media): the information is stored in nodes and the relations are mentioned (for example network of friends of an individual)
- The objective is to add horizontal scalability to the performance of a relational model.
- It combines the performance NoSQL and accessibility of relational databases models (see Storing Data: ACID)
Reference: Big Data: A very short introduction by Dawn E. Holmes. Oxford University Press, 2017