Proxysql 2.7.1 with MySQL 8.0 Integration Error: "Unknown system variable 'query_cache_size'"

[colozhan]

System Environment:

Operating System: RockyLinux 9
MySQL Version: 8.0
Proxysql Version: 2.7.1-1-centos9.x86_64.rpm
Installation Method: Installed via RPM package
Issue Description:
When integrating Proxysql 2.7.1 with MySQL 8.0, the service starts without any errors. However, when the application connects to MySQL through Proxysql, the following error is thrown:
Unknown system variable 'query_cache_size'
There is no error when the application directly connects to MySQL 8.0 without Proxysql.

Steps to Reproduce:

Install Proxysql 2.7.1 and MySQL 8.0 on a RockyLinux 9 system.
Configure Proxysql as a proxy for MySQL.
Start the Proxysql service.
Attempt to connect to MySQL via the application through Proxysql, and the error "Unknown system variable 'query_cache_size'" occurs.
Directly connect to the MySQL 8.0 database, no errors.
Expected Result:
I would like to resolve the compatibility issue between Proxysql and MySQL 8.0, and avoid the "Unknown system variable 'query_cache_size'" error.

Solutions Already Attempted:

Checked Proxysql configuration files to ensure query_cache is not explicitly enabled.
Verified that the MySQL configuration has the query_cache-related options disabled.
Ensured compatibility of Proxysql version with MySQL 8.0.
Additional Information:

MySQL 8.0 has disabled the query_cache_size by default, but Proxysql seems to still attempt to load this parameter when processing queries. Assistance in resolving this compatibility issue would be appreciated.

[renecannao]

Attempt to connect to MySQL via the application through Proxysql, and the error "Unknown system variable 'query_cache_size'" occurs.

You mean that your application is querying query_cache_size. Most probably, you are using JDBC , that is assuming that query cache is enabled because of MySQL version advertised.

Configure mysql-server_version accordingly.
If you are using a mix of backends of different version, create a query rules that replace querying query_cache_size with a zero.

Thanks.