NoSQL stands for “Not Only SQL”, and it is a database model and unlike Relational Database it does not use tables to store data. There are various types of NoSQL database present in the digital market and their types generally depend on the data models they store. Some of the major NoSQL types are document, key-value, wide-columns and graphs. NoSQL database performance is faster than a relational database and its database are more scalable with high user load.
What is NoSQL?
In simple term when we say a NoSQL database, we simply mean a non-relational database, which does not use table-like structure to store data. Some developers refer NoSQL as “non-SQL” and other “Not Only SQL”, even Wikipedia defies NoSQL as “non-SQL”. But at the end, all NoSQL database developers agree on one concept that NoSQL databases are the databases that do not follow relational table data structure to organize and manage the data.
Not to follow the concept of Relational-Database or tabular structure has nothing to do with the relation (related) data in the database. The NoSQL database can use the relationship between data to manage and organize records but the data would not be formatted like relational rows and columns. NoSQL also follows some relational tactics so the relational ship data can also be stored in the database. Many developers find the relational data of NoSQL easier than Relational database because unlike a Relational database the NoSQL database does not split or divide its data into multiple tables.
Common Type of SQL Databases
There are 4 common types of NoSQL databases
- Document Database
- Key-Value Database
- Wide Column Database
- Graph Database
1. Document Database
The NoSQL Document Database use the JSON like object to store data. The document contains the pairs of fields and values where fields are the attributes and values are the actual data or record. And the value data can be of any data type such as string, numbers, boolean, array or object. NoSQL document databases contain a wide variety of data types and powerful & robust query languages, which make it a great database choice for a large data volume business. MongoDB which is one of the most popular NoSQL databases works on the Document Database model.
2. Key-value database
The key-value database uses a pair of the key-value object to store data and its attribute. To retrieve the data from the database we can use the data corresponding key. key-value database true power and potential came in use when we want a large database where we do not want to use complex queries. DynamoDB and Redis NoSQL databases uses the Key-value Database models.
3. Wide-Column Database
Wide-Column Database uses a table-like data structure to store its data, but it is different from Relational Database, unlike rows and fixed columns, NoSQL use Dynamic Columns. In Wide-Columns database it is not necessary that each row record has to follow the same column. This dynamic column approach of the wide-columns database gives it more flexibility over the relational databases. The developers choose wide-columns databases for those projects where we need to store a large amount of data and the query patterns are already predicted, IoT is the classical example of a wide-columns database in use. Cassandra and HBase are two widely used wide-columns store databases.
4. Graph Databases
Like a normal Graph Data Structure, Graph Database also uses the concept of nodes and edges to store data. Here the node represents the real-entity or data such as people, & things, and the edges represent the relation between the nodes or data. Right now, in Machine learning and Artificial Intelligence models Graph Database, it likely used, because its very easy to traverse in this database and relationship between the data can be easily represented. Neo4j and Janus Graph are the two most popular NoSQL Databases which use the graph database.
Advantages and Disadvantages of NoSQL Databases
Like every technology NoSQL has some merits and demerits let’s have a look on both.
- NoSQL databases come with high scalability and they can load data faster than a relational database.
- The cost of the NoSQL is also very low as compared to a relational database.
- It comes with a feature of auto replication, in case if the database fails to fetch data the auto replication uses the previous data.
- NoSQL is only oriented to store data and it lacks in other database functionalities.
- Graphical Tools for NoSQL are not available in the market.
- In many NoSQL databases, it has seen that the backup process is not consistent.
- NoSQL database generally has large document size. The similar data in a relational database would occupy less space.
NoSQL is generally preferred by those businesses which only want to focus on data storage and do not want to spend much on a database. Developers also like this database because it can even store unstructured data, which means developers does not need to define the database schema before storing data. In past few years, Cloud Computing also gained too much popularity amongst technical and non-technical user, and many NoSQL databases come with the capability of scalability, distributed data and application resilient properties which make them a perfect database for cloud storage.