Difference between SQL and NoSQL

SQL vs. NoSQL | Difference between SQL and NoSQL

Choosing a database is the most fundamental decision that needs to be decided before starting a task. Relational and non-relational databases are both feasible data structures.

SQL is a relational database, whereas NoSQL is a non-relational database.

There are some crucial differences between the two databases that users have to keep in mind while choosing between them.

What are SQL databases?

SQL databases or Structured Query Language, as they are known, are used for defining the data and manipulating them. It is a powerful as well as a flexible language designed to deal with databases. Also, it is one of the most widely used languages. It requires the user to use schemas for establishing the structure of the data. All the data must follow that particular structure.

What are NoSQL databases?

NoSQL databases are designed in such a way that they can deal with unstructured data, and do not require schemas like SQL. It is also very dynamic in nature and allows the storage of data in many forms. It allows each document to have its own structure, and the syntax varies from one database to another. Also, data fields can be added as and when required.

Key Differences between SQL and NoSQL

There are certain key differences between these two types of databases that need to be kept in mind before choosing between them.

• Type: SQL databases are known as Relational Databases (RDBMS), this implies that SQL databases store the data in the form of tables that form relations between them. Whereas, NoSQL databases are known as non-relational databases.
• Language: SQL is a very powerful and adaptable language, but it can be restrictive at the same time. It allows the user to store data only in the form of some predefined structures or schemas. This requires a lot of preparation up-front. But on the other hand, NoSQL is more dynamic than SQL and allows databases to have their own structure and syntax.
• Scalability: In most cases, SQL is vertically scalable. This means that the single server load can be increased by enhancing the RAM, CPU, and SSD. But, unlike SQL, NoSQL is horizontally scalable. This means that more traffic can be managed only by sharding or adding more servers to the database. Thus, in the end, NoSQL databases can become larger and more powerful.
• Structure: SQL stores databases in the form of tables. On the other hand, NoSQL stores data in the form of key-value pairs, document-based, graph databases, or wide-column stores. Thus, SQL databases are more suitable option for applications that require multi-row transactions.
• Property: SQL follows ACID properties (Atomicity, Consistency, Isolation, Durability). NoSQL follows Brewer’s CAP theorem (Consistency, Availability, Partition).
• Support: SQL databases avail great help from their vendors. Many independent consultations also support SQL databases, especially for large-scale deployments. For NoSQL databases, in some cases, one still has to depend on community support, and there are fewer experts as compared to SQL databases which can set up NoSQL deployments for a large scale. Examples of SQL databases include MySQL, Microsoft SQL Server, Oracle, and PostgreSQL. Examples of NoSQL include MongoDB, CouchDB, Redis, HBase, Neo4j, Google Cloud, BigTable.

Difference chart between SQL and NoSQL

Some of the crucial differences between SQL and NoSQL are listed below in a tabular manner:

SQL	NoSQL
It is Relational Database (RDBMS).	It is Non-relational database.
It contains predefined and fixed schemas.	It does not have predefined or fixed schemas and varies according to the requirement of the database.
SQL is more suited for queries that are more complex in nature.	NoSQL is more suited for queries that are not so complex.
SQL is scalable vertically.	NoSQL is scalable horizontally.
SQL follows ACID property.	NoSQL follows CAP tolerance.
SQL databases are not suitable for storage of hierarchical data.	NoSQL databases are better matched for hierarchical data storage.

SQL and NoSQL- Which is better?

Both these databases have their individual advantages and disadvantages. There has been a constant manoeuvre to integrate the two by taking their best characteristics to help the better users experience of both the databases.

For example, MySQL, which is the most popular SQL database, extends MySQL Document Store. This provides the schema of a SQL database along with the flexibility and availability of NoSQL, and this does not require the implementation of a separate NoSQL database.