In recent conversations, it would be very helpful to capture the last 'x' queries used by a particular index. This will further help identify "unused" indexes as well as help identify which queries/indexes could be combined for better efficiency.
I'm thinking about a case where an application has been in production for 5 years, is implemented across multiple microservices, each of which has gone through multiple versions. The cluster has >200 indexes. The use case here is to give a DBA information about which of those indexes could be removed or consolidated.
The last used time is useful, but leaves open the possibility for a false positive on an index that is used weekly/monthly. The next most helpful data would be for Couchbase to provide data on the last query that was run against each index.
Yes it would take resources, so turning it on/off would be required...but any sort of profiling provides benefit at the cost of resources.