MySQL 5.7 vs MySQL 8: Key Differences and When to Use Each

MySQL 8 introduces major improvements over MySQL 5.7 including better performance, enhanced security, and new SQL features like window functions and common table expressions (CTEs). It also supports UTF8MB4 by default and has improved JSON support, making it more modern and efficient for today's applications.

Quick Comparison

This table summarizes the key differences between MySQL 5.7 and MySQL 8 to help you quickly understand their main distinctions.

Feature	MySQL 5.7	MySQL 8
Default Character Set	latin1	utf8mb4
Window Functions	Not supported	Supported
Common Table Expressions (CTEs)	Not supported	Supported
JSON Support	Basic JSON functions	Enhanced JSON functions and indexing
Security	Basic authentication plugins	Improved default authentication and roles
Performance	Good	Improved optimizer and better indexing
Data Dictionary	File-based	Transactional, integrated data dictionary

Key Differences

MySQL 8 brings significant improvements over MySQL 5.7 in multiple areas. One major change is the default character set: MySQL 8 uses utf8mb4 by default, which fully supports all Unicode characters including emojis, while MySQL 5.7 defaults to latin1. This makes MySQL 8 better suited for modern applications requiring full Unicode support.

Another important difference is the addition of advanced SQL features in MySQL 8 such as window functions and common table expressions (CTEs). These features allow more powerful and readable queries, which were not available in MySQL 5.7. JSON support is also enhanced in MySQL 8 with better functions and indexing capabilities, improving performance for JSON data handling.

Security and performance have been improved in MySQL 8 as well. It introduces a transactional data dictionary replacing the file-based one in MySQL 5.7, which improves reliability. Authentication plugins and role-based access control are enhanced, making it easier to manage user permissions securely. The query optimizer is also more advanced, leading to faster query execution in many cases.

Code Comparison

Here is an example of how to create a common table expression (CTE) in MySQL 5.7, which is not supported and will cause an error.

sql

WITH recent_orders AS (
  SELECT order_id, order_date
  FROM orders
  WHERE order_date > '2023-01-01'
)
SELECT * FROM recent_orders;

Output

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'WITH recent_orders AS ( SELECT order_id, order_date FROM orders WHERE order_date > '2023-01-01' ) SELECT * FROM recent_orders' at line 1

MySQL 8 Equivalent

The same query using a CTE works perfectly in MySQL 8:

sql

WITH recent_orders AS (
  SELECT order_id, order_date
  FROM orders
  WHERE order_date > '2023-01-01'
)
SELECT * FROM recent_orders;

Output

[{ "order_id": 101, "order_date": "2023-02-15" }, { "order_id": 102, "order_date": "2023-03-10" }]
-- Example output assuming matching data

When to Use Which

Choose MySQL 8 when you need modern SQL features like window functions, CTEs, or full Unicode support with utf8mb4. It is also better for applications requiring improved JSON handling, enhanced security, and better performance.

Use MySQL 5.7 if you have legacy systems that depend on it or if your environment does not yet support upgrading. However, for new projects, MySQL 8 is the recommended choice due to its advanced capabilities and ongoing support.

Key Takeaways

MySQL 8 supports advanced SQL features like window functions and CTEs, unlike MySQL 5.7.

UTF8MB4 is the default character set in MySQL 8, enabling full Unicode support.

MySQL 8 offers improved JSON functions, security, and performance enhancements.

Choose MySQL 8 for new projects and modern applications requiring these features.

Use MySQL 5.7 only for legacy compatibility or environments where upgrading is not possible.