Difference Between SQL and NoSQL Database

If you are an engineer, data analyst, or IT decision maker, you might already know about the Relational Database Management System (RDBMS), enabling you to access data in relation to some other piece of data present in the database. Moreover, you may also be aware of Structured Query Language (SQL), i.e., a programming language used to interact with the data stored in the RDBMS. Now, the emergence of alternative NoSQL databases has left you wondering what is the difference between SQL and NoSQL, right?

Well, this article makes the comparison between SQL and NoSQL easier for you. Through this write-up, we do a detailed SQL vs NoSQL analysis.

To make a comprehensive comparison between these two databases, it is crucial to understand them in isolation. Hence, let us begin with a brief understanding of SQL and NoSQL.

SQL in SQL vs NoSQL

SQL, i.e., Structured Query Language lets you communicate with the data present in a Relational Database Management System. Its syntax resembles English, making it simple to understand, write, and read. You can find the use of SQL and its variants in many relational databases.

NoSQL in SQL vs NoSQL

NoSQL, i.e., Non SQL or Not Only SQL is a non-relational database that stores data in a form different from the relational databases. The following figure shows the features of NoSQL for which it gained popularity.

Now that you have a slight understanding of the two databases, it is time to look at the differences between SQL and NoSQL databases.

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SQL vs NoSQL: The Key Differences

This section of the article focuses on what is the difference between SQL and NoSQL. The following are the core differences between these two databases.

1. Language

Over 40 years old, SQL is a versatile language. It is used and recognized widely. You may often find its use where complex queries are involved. However, SQL is quite restrictive as you must use predetermined schemas to know your data’s structure before working with it. It makes structure changes quite cumbersome.

Whereas unstructured data in NoSQL has a dynamic schema. Moreover, there are many ways of data storage, such as column-oriented, document-oriented, graph-based, or data organized as a key value. This flexibility eliminates the need to predefine the data structure. Moreover, NoSQL permits each document to have its own structure, unlike SQL.

Talking about the language dialects, SQL has a lot of them. And each SQL dialect is almost identical in grammar and syntax. On the other hand, NoSQL language dialects are not so consistent. They concern a different and often unrelated technology set.

2. Scalability

SQL databases offer vertical scalability. You can increase items like RAM, SSD, or CPU to increase the load on a particular server. It is possible to scale the SQL databases horizontally, but it does not support the sharding or partitioning logic well.

NoSQL databases have horizontal scalability. You can perform sharding or the addition of extra servers in the database to cope with more traffic. Moreover, it also boasts options for vertical scalability.

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Type of properties

SQL databases use ACID (Atomicity, Consistency, Isolation, and Durability) properties. Let us look at a short explanation of each of these properties.

Properties of SQL

• Atomicity stands for all transactions that must either succeed or fail totally. They cannot be partially successful even if the system fails.

• Consistency implies each database step follows invariants, i.e., rules which do not vary.

• Isolation means no concurrent transaction affects another transaction. All transactions remain unaffected by each other.

• Durability is making the transaction final. Even if the system fails, it is not possible to reverse a successful transaction’s effects.

Unlike SQL, NoSQL follows CAP, i.e., Consistency, Availability, and Partition tolerance properties. Below is a brief description of each of them.

Properties of NoSQL

• Consistency implies that each request’s result is the most recent one.

• Availability means the result of every request is non-error, no matter how recent the result is.

• Partition Tolerance is any node delays or losses not interfering with the system’s operation.

In a NoSQL database, only two of the above properties are possible at a single time.

Structure

The structure in SQL is table-based. It follows the rules of integrity and consistency. Moreover, each attribute (column), records (rows), and keys of the SQL structure show a logical relationship.

NoSQL follows a column-oriented, key-value, document, graph-based structure.

Support

Since SQL databases are quite well-established, they have widely available support in the form of huge communities, individual consultations, and codebases. Whereas, NoSQL users have to rely mostly on small communities and a limited number of outside experts for support.

Now, let us tabulate the above points to give you a precise answer to the question: what is the difference between SQL and NoSQL.

SQL vs NoSQL: Key Highlights

The following table highlights the key differences between SQL and NoSQL.

After learning how SQL and NoSQL differ from each other, let us answer the question of when to use SQL and NoSQL.

Use Cases of SQL and NoSQL

Below are the instances when you should use SQL.

• Complex queries: SQL is a better option when you need to work with complicated queries and reports. It can create one script for data retrieval and presentation.

• Complex transactions: Stability and data integrity make SQL a better fit for complex transactions.

• ACID compliance: SQL is the perfect choice when it comes to compliance with the ACID (Atomicity, Consistency, Isolation, and Durability) properties.

• Large data volumes: Where there is a large amount of data with no much-anticipated change or growth, it is a wise decision to use SQL. Moreover, SQL is also preferred for instances involving many data types.

Now, let us discuss why to use NoSQL over SQL.

• Constant feature addition: Using NoSQL is recommended when you want to keep adding more features, data types, and functions. It makes predicting the application’s growth easier.

• Data model changes: NoSQL is better than SQL for making changes in the data model easily.

• Many data types: NoSQL can easily store data of many kinds without you spending time defining the kind of data you are storing.

SQL vs NoSQL: The Conclusion

This article discussed the differences between SQL and NoSQL. You may go through the above write-up to understand these databases, their differences, and their uses in detail.

You may drop your questions, doubts, or suggestions about this post, if you have any, in the comments section.