NoSQL

            NoSQL databases are used to any non-relational databases. Some say the term that “NoSQL” stands for “NonSQL” stands while others say it stands for “no only SQL”. NoSQL databases are stored date in a format other than relational tables. MongoDB is consistently ranked as the world’s most popular NoSQL database.

            NoSQL data bases can store relationship data-they just store it differently than relational databases do. NoSQL data models allow related data to be nested within a single data Days were needing to create a complex, difficult-to-manage data model simply for the purposes of reducing data duplication. The developers of NoSQL databases were becoming the optimized for developer productivity.

Differences of SQL vs NoSQL

SQL	NoSQL
Relational	Non-relational
Structured query language and have a predefined schema.	Unstructured data and have dynamic schema
Vertically scalable.	Horizontally scalable.
Table based structure.	Document, key-value, graph or wide-column stores.
Better for multi-row transactions.	Better for unstructured data like documents or JSON.

Wikipedia definition for NoSQL

           “A NoSQL (originally referring to "non-SQL" or "non-relational") database provides a mechanism for storage and retrieval of data that is modeled in means other than the tabular relations used in relational databases. Such databases have existed since the late 1960s, but the name "NoSQL" was only coined in the early 21st century, triggered by the needs of Web 2.0 companies. NoSQL databases are increasingly used in big data and real-time web applications.”

Types of NoSQL

·         Document databases are store data in documents similar to JSON (JavaScript Object Notation) objects. Each document contains pairs of field and values. The value can be containing of strings, numbers, Booleans, arrays, or objects.

 

·         Key-value databases are s similar type of databases where each item contains key and values. This type of databases is used for where you need to store large amount of data but you don’t need to perform complex queries to retrieve it.

 

·         Wide-column stores data in tables, rows, and dynamic columns. Wide-column stores provide a lot of flexibility over relational databases because each row is not required to have the same columns. This type of databases is great for when you need to store large amounts of data and you can predict what query pattern will be and it also commonly used to store IOT (Internet of Things) data and user profile data.

 

·         Graph databases store data is nodes and edges. Node store information about people, place, and things while edges store information about the relationships between the nodes. Neo4j and Janus Graph are the examples of graph databases.