GitHub user TheBuilderJR added a comment to the discussion: [Ideas] Add 
instrumentation and latency metrics to the Anser subsystem

For the `anser.stats()` / `stats_reset()` contract, could each snapshot 
identify its reset generation, and could the API document how a reader knows a 
reset has completed? A consumer computing interval rates from cumulative 
counters needs to distinguish two reads that straddle a reset. Checking for a 
negative delta alone can miss the reset if enough new activity has already 
exceeded the previous count.

This also affects interval histogram quantiles: subtract corresponding bucket 
counts only across compatible snapshots from one reset generation, then derive 
an approximate quantile from that interval distribution; subtracting the 
displayed p99 values would not give an interval p99. Given the no-new-locks 
constraint, stating whether count, total time and bucket reads are a 
best-effort snapshot would help consumers avoid asserting exact consistency 
during concurrent updates.

This is feedback on the proposed API, not a reproduced implementation issue. 
Disclosure: I build Telemetry; this reply was drafted with AI assistance.

GitHub link: 
https://github.com/apache/cloudberry/discussions/1958#discussioncomment-18319661

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