# Relational vs. Non-Relational Databases

## Relational vs. Non-Relational Databases

### Relational database 

A relational database, or relational database management system (RDMS), stores information in tables. Often, these tables have shared information between them, causing a relationship to form between tables. This is where a relational database gets its name from.

<figure><img src="/files/SgC2qtbchLqP9lzR9Xbp" alt=""><figcaption><p><em>Data is stored as tables with rows and columns in a relational database</em></p></figcaption></figure>

The details of the product are in a separate product table. This makes information organized and more structured.

#### Advantages of relational databases <a href="#advantages-of-relational-databases" id="advantages-of-relational-databases"></a>

ACID compliance

Data accuracy

Normalisation&#x20;

#### Disadvantages of relational databases <a href="#disadvantages-of-relational-databases" id="disadvantages-of-relational-databases"></a>

Flexibility&#x20;

Scalability&#x20;

Performance

### Non-relational database

#### What is a non-relational database? <a href="#what-is-a-nonrelational-database" id="what-is-a-nonrelational-database"></a>

A non-relational database, sometimes called NoSQL (Not Only SQL), is any kind of database that doesn’t use the tables, fields, and columns structured data concept from relational databases. Non-relational databases have been designed with the cloud in mind, making them great at horizontal scaling.

There are a few different groups of database types that store the data in different ways:

Document databases

Key-value databases

Graph databases&#x20;

Wide-column databases

Document databases store data in documents, which are usually JSON-like structures that support a variety of data types. These types include strings; numbers like int, float, and long; dates; objects; arrays; and even nested documents. The data is stored in pairs, similar to key/value pairs.

Consider the same customer example as above. In this case, however, we are able to view all the data of one customer in a single place as a single document:

<figure><img src="/files/x08ToBIY8r8UddVCKB3B" alt=""><figcaption><p><em>How data is stored in a document non-relational database</em></p></figcaption></figure>

Due to documents being JSON-like, they are much easier to read and understand for a user. The data is organized, and also easy to view. There is no need to reference multiple documents or collections to view data of a single customer. The documents map nicely to objects in code in object-oriented programming languages, making it much easier to work with.

### How do they compare

<figure><img src="/files/UzueXCHc1xKvnywST6c7" alt=""><figcaption></figcaption></figure>

### When to use a relational database <a href="#when-to-use-a-relational-database" id="when-to-use-a-relational-database"></a>

Data is predictable in terms of structure size and frequency of access

Normalisation is a must to keep the size of data low&#x20;

There is complex relationship between participating entities

You need to work with existing tool sets

### When to use a non-relational database <a href="#when-to-use-a-nonrelational-database" id="when-to-use-a-nonrelational-database"></a>

Data keeps varying in terms of their structure and size

Your application is distributed across multiple nodes on a cloud

Where we need low latency and eventual consistency

### Summary

<figure><img src="/files/gqNtsJiv4wLnObK0IySq" alt=""><figcaption></figcaption></figure>

### Read more

{% embed url="<https://www.mongodb.com/compare/relational-vs-non-relational-databases>" %}


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