To migrate older applications to MySQL 8.0 successfully, first check application compatibility, then carefully migrate and convert data, update configuration and security settings, and monitor performance post-migration. 1. Check application compatibility by updating database drivers or temporarily configuring MySQL to use older defaults like mysql_native_password and utf8mb4. 2. Migrate data carefully by converting MyISAM tables to InnoDB, using mysqldump with --default-character-set=utf8mb4, and setting default character sets and collations appropriately. 3. Update configuration files and security settings, including sql_mode, max_allowed_packet, and user authentication plugins, while tightening permissions and removing unused accounts. 4. Monitor performance after migration using tools like mysqltuner.pl, enable the slow query log, and verify backup integrity to ensure a stable and optimized environment.

Migrating older applications to MySQL 8.0 can unlock performance improvements, better security, and access to new features—but it’s not always a straightforward process. Compatibility issues, deprecated features, and configuration changes can trip you up if you’re not prepared.

Here’s how to approach the migration with fewer headaches.

Check Application Compatibility with MySQL 8.0

Before you start moving data or changing configs, you need to make sure your application will work with MySQL 8.0.

MySQL 8.0 dropped support for some older syntax and features. For example, the utf8 character set is now effectively utf8mb4, and the default authentication plugin changed from mysql_native_password to caching_sha2_password.

If your app uses an older version of a database driver or connector (like JDBC or PHP’s mysqli), it might not support these new defaults. You’ll need to either:

• Update the application’s database driver to a version compatible with MySQL 8.0
• Configure MySQL to use the older authentication plugin and character set (temporarily)
• Test database queries that might rely on deprecated syntax

A good way to start is by running your app against a test instance of MySQL 8.0 before doing a full migration.

Migrate and Convert Your Data Carefully

Once compatibility looks good, it’s time to move the data. But don’t just dump and restore and call it a day.

Older databases might be using MyISAM tables, which are still supported but no longer the default. If you’re moving to MySQL 8.0, consider switching to InnoDB for better performance and reliability.

Also, check your character sets and collations. If your old database used latin1 or utf8, you’ll want to convert to utf8mb4 to support full Unicode (including emojis and special characters). This can be done during migration using ALTER DATABASE and ALTER TABLE statements.

Here’s a quick checklist:

• Use mysqldump with --default-character-set=utf8mb4
• Convert tables to InnoDB: ALTER TABLE your_table ENGINE=InnoDB
• Set default character set to utf8mb4 in your MySQL config
• Double-check collation settings, especially if your app is case-sensitive or language-specific

This step takes some planning, but it ensures your data stays clean and works well with modern applications.

Update Configuration and Security Settings

MySQL 8.0 introduced several security enhancements, and some defaults are stricter than in older versions.

For example, user authentication is more secure by default, but that can break apps that expect the older password plugin. If you can’t update the app’s database connector right away, you can create users with the old plugin temporarily:

CREATE USER 'app_user'@'%' IDENTIFIED WITH mysql_native_password BY 'your_password';

Also, review your my.cnf or my.ini file. MySQL 8.0 deprecates some configuration options and introduces new ones. If you had custom settings for query cache or MyISAM-specific tuning, those may need to be removed or adjusted.

Here are a few other config items to double-check:

• sql_mode – MySQL 8.0 has a stricter default mode
• max_allowed_packet – Adjust if you’re working with large datasets
• innodb_file_per_table – Should be enabled for better manageability

Security-wise, take the opportunity to clean up user permissions. Remove unused accounts and tighten access rules.

Monitor and Optimize After Migration

After the migration is done, keep an eye on performance and errors.

Use tools like mysqltuner.pl or built-in performance schema to spot bottlenecks. You might notice differences in query performance—especially if you switched from MyISAM to InnoDB or changed character sets.

Enable the slow query log to catch any inefficient queries that slipped through testing. You can do that by adding:

slow_query_log = 1
long_query_time = 1
log_slow_queries = /var/log/mysql/mysql-slow.log

Also, make sure your backups are working with the new setup. Test a restore from your latest dump to confirm everything is in order.

Migrating legacy apps to MySQL 8.0 doesn’t have to be a nightmare. With a little planning and testing, you can modernize your database stack without breaking what already works. Just don’t skip the compatibility checks and take time to optimize after the move.

The above is the detailed content of Migrating Legacy Applications to MySQL 8.0. For more information, please follow other related articles on the PHP Chinese website!