MariaDB JSON Data Type

In this comprehensive MariaDB tutorial, I’ll walk you through everything you need to know about the MariaDB JSON data type—from its basics and advantages to practical methods for using JSON in your databases.

MariaDB JSON data type

We’ll learn about the MariaDB JSON data type in this part, which is described with illustrated syntax and an example.

What Is the MariaDB JSON Data Type?

JSON (JavaScript Object Notation) is a lightweight, text-based format for representing structured data. It’s widely used in web APIs, configuration files, and NoSQL databases.

MariaDB’s JSON data type is a replacement for LONGTEXT, which was designed to work with MySQL’s JSON data type. Because it violates the SQL standard, MariaDB supports the JSON data format as a LONGTEXT instead, and MariaDB’s benchmarks show that efficiency is at least comparable.

Key Features

Feature	Description
Storage	JSON stored as LONGTEXT with utf8mb4_bin collation
Validation	No strict JSON validation on insert, but functions expect valid JSON
JSON Functions	Rich set of functions like JSON_EXTRACT, JSON_SET, JSON_ARRAY
Indexing	No native JSON indexes, but functional indexes on JSON expressions are possible
Integration	Works seamlessly with MariaDB’s SQL engine and replication

How to Define a JSON Column in MariaDB

Creating a table with a JSON column is straightforward. Since JSON is an alias for LONGTEXT, you can declare your column as JSON or LONGTEXT with the appropriate collation.

EXAMPLE:

Creating a Table with JSON Column

In the query below, we have created a table called JSON_DEMO with columns as USER_NAME and JSON_VALUE. The JSON Datatype generates the JSON_VALUE column. After executing the query below, the table was created successfully, as shown in the screenshot below.

CREATE TABLE Json_demo(
user_name varchar(20) not null,
json_value json
CHECK(JSON_VALID(json_value)));

Inserting JSON Data into MariaDB

In the second query, we have inserted one record in the JSON_DEMO table by using the INSERT INTO statement.

INSERT INTO JSON_DEMO(user_name,json_value)
values('JohnY_K','{"json_id":1,"json_name":"Anthony"}');

After executing the above query, the data was inserted successfully, as shown in the screenshot below.

Querying JSON Data in MariaDB

In the query below, we attempted to retrieve all records, including JSON datatype values, from the JSON_DEMO table using the SELECT statement. Check out the screenshot below for your reference.

SELECT * FROM JSON_DEMO;

Check out Column count doesn’t match value count at row 1

Performance

The primary benefit of using the JSON datatype in MariaDB is that it offers two advantages over storing JSON strings in text fields, including data validation. The JSON documents will automatically be validated, and invalid documents will produce an error.

The JSON VALID function can be used rather than the CHECK constraint to ensure that a valid JSON document is stored. This constraint is automated and includes types from MariaDB 10.4.3’s JSON alias.

Best Practices When Using JSON Data Type in MariaDB

Best Practice	Explanation
Validate JSON Before Insert	Use application logic or MariaDB functions to ensure valid JSON
Use Functional Indexes Wisely	Index frequently queried JSON paths for performance
Avoid Overusing JSON	Use JSON for flexible data, but prefer normalized tables for structured data
Use Proper Collation	Use utf8mb4_bin collation for JSON columns to ensure binary comparison
Monitor Query Performance	Analyze slow queries involving JSON functions

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Advantages and Limitations

Advantages	Limitations
Easy to store semi-structured data	No native binary JSON storage (uses LONGTEXT)
Rich JSON function support	No automatic JSON validation on insert
Compatible with MySQL JSON syntax	Limited indexing options compared to other DBs
Flexible for evolving data models	Larger storage size compared to binary JSON

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Why Use MariaDB JSON Data Type? Use Cases

• E-commerce platforms: Store product specifications and customer preferences.
• Healthcare applications: Manage flexible patient records and metadata.
• Financial services: Store transaction metadata and audit trails.
• IoT systems: Capture sensor data with varying attributes.

Read: MariaDB Reserved Words

Conclusion

The MariaDB JSON data type offers a powerful way to handle semi-structured data within a relational database. While it doesn’t have native binary JSON storage like some competitors, MariaDB compensates with a rich set of JSON functions and compatibility with MySQL’s JSON syntax.

You may also like to read the following MariaDB tutorial.

• MariaDB vs Postgres
• MariaDB Drop Table
• MariaDB COUNT Function
• MariaDB Variables Tutorial
• MariaDB Insert If Not Exists