v.20.3Improvement

Add Metric for Tracking Client Connections via MySQL Protocol

Add a system metric tracking the number of client connections using MySQL protocol (#9013). #9015 (Eugene Klimov)
Added a system metric to track the number of client connections using the MySQL protocol in ClickHouse.

Why it matters

This feature provides visibility into MySQL protocol client connections, allowing users and administrators to monitor and manage connection counts accurately. It helps identify usage patterns and diagnose connectivity-related issues in environments where the MySQL protocol is used to communicate with ClickHouse.

How to use it

The metric can be accessed via ClickHouse's system metrics interface. Users can query the relevant system table or monitoring endpoint that exposes the number of active MySQL protocol connections to observe or integrate this data into their monitoring tools.