Problem

While discussing the EOT (end-of-transaction) event counter, Jan Steemann noted we don't have generic per-operationType event counters for regular change stream events. Today we can count control events and specific special-case events, but nothing tells us the volume breakdown of ordinary operations flowing through a change stream.

Proposal

Add counters keyed by operationType for regular events, e.g.:

• insert
• update
• delete
• drop
• shardCollection
• (and other operation types as applicable)

This would give visibility into workload composition per stream without needing to sample or log individual events.

Dependency

Builds on the V2 state machine / control event observability work in SERVER-135656 (that ticket's control event counters establish the pattern this would extend to regular events).

Related Files

• src/mongo/s/change_streams/