v.24.10Improvement

Add readonly_duration column to system.replicas table for replica distinction

Add new column readonly_duration to the system.replicas table. Needed to be able to distinguish actual readonly replicas from sentinel ones in alerts. #69871 (Miсhael Stetsyuk).
Added a new column readonly_duration to the system.replicas table in ClickHouse.

Why it matters

This feature allows users to distinguish between actual readonly replicas and sentinel replicas in alerts, improving monitoring accuracy and operational clarity.

How to use it

Query the system.replicas table to access the new readonly_duration column, which shows the duration a replica has been in readonly mode.