To clear the database cache in MySQL 8 InnoDB, you can follow these steps:
- Connect to the MySQL server using the SQL client (e.g., MySQL command-line client, phpMyAdmin, or MySQL Workbench).
- Issue the following SQL query to check the current cache size and status:
SHOW VARIABLES LIKE 'innodb_buffer_pool_size';
- If the cache is dynamically allocated, you can clear it by changing the value of the innodb_buffer_pool_size variable. Set it to a lower value to force the cache to clear. For example, if the current value is 4G, you can set it to 2G using the following SQL query:
SET GLOBAL innodb_buffer_pool_size = 2G;
- Wait for a few minutes to allow the cache to clear. You can check the progress by monitoring the status of the Innodb_buffer_pool_bytes_data variable. For example, you can issue the following SQL query:
SHOW GLOBAL STATUS LIKE 'Innodb_buffer_pool_bytes_data';
- Once the cache has cleared, you can restore the original buffer pool size by setting the innodb_buffer_pool_size variable back to its original value. For example:
SET GLOBAL innodb_buffer_pool_size = 4G;
Note that clearing the cache will result in decreased performance until the cache is refilled with data from disk. Additionally, if you have a dedicated MySQL server, it's recommended to schedule regular server restarts to clear the cache and provide a fresh start.