Cumulative Metrics (increase with time and can be recorded for a period (like 'Key_reads', 'Maximum no. of Connections that Ever Was')) are calculated differently instead of point-in-time metrics (like 'Server Availability', 'Currently Running Threads').
- Cumulative metrics: SQL DM for MySQL send alert if thresholds are crossed for last collection interval.
- Point-in-time metrics: SQL DM for MySQL send alert only based on 'Current' values (for instance current no. of connections is close to Max Allowed Connections - there is nothing more to consider!).