lifetime_rows/lifetime_bytes Added for Buffer Engine

Why it matters

This feature provides users with cumulative statistics on the total number of rows and bytes processed by the Buffer engine over its lifetime. It helps in monitoring and analyzing resource usage and throughput for Buffer tables, enabling better performance tuning and capacity planning.

How to use it

Users can access the lifetime_rows and lifetime_bytes metrics for Buffer engine tables via the existing system tables or monitoring tools that query engine statistics. No additional configuration is required to start collecting these lifetime metrics once the new version with this feature is deployed.