# Rate calculation results in hugely unexpected exponential values **URL:** \ **Category:** General Help/Support\ **Created:** [December 1, 2021, 4:17pm UTC](https://discuss.prometheus.io/t/rate-calculation-results-in-hugely-unexpected-exponential-values/621 "2021-12-01T16:17:06Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![akikul](https://dub1.discourse-cdn.com/flex017/user_avatar/discuss.prometheus.io/akikul/32/285_2.png) [@akikul](https://discuss.prometheus.io/u/akikul)\ **Post date:** [December 1, 2021, 4:17pm UTC](https://discuss.prometheus.io/t/rate-calculation-results-in-hugely-unexpected-exponential-values/621/1 "2021-12-01T16:17:06Z")
A basic description of the issue is that when we are querying `rate(api_heartbeat_seconds_bucket{le="1.0",instance="SITE-A:1234"}[2m])` we have unexpected spikes in the rate: Fig 1 But when we query without the rate the `api_heartbeat_seconds_bucket{le="1.0",instance="SITE-A:1234"}` the increased steps are smooth: Fig 2 Background: We were scraping from three different Prometheus nodes back to one Prometheus Federated and we saw that there was a very small difference between the Prometheus nodes; diff of 1 or 2 (let me know if you want to see the data from each node); so decided to scrape one node to test if this made any difference. We saw that since then we have not had any spikes. Fig 3 It is strange as we have had the multi-target configuration in place for months and it has only become an issue over the last couple of weeks. FYI: scrape\_interval: 15s scrape\_timeout: 10s evaluation\_interval: 1m The questions: 1. is this a coincidence and actually, something else is at play. 2. Why would the rate extrapolation be so sensitive and unpredictable 3. I assume that the reason when we query `api_heartbeat_seconds_bucket{le="1.0",instance="SITE-A:1234"}` as smoothed steps are that there is some smoothing going on when Prometheus runs this query, is this correct? 4. Could I check something to provide the route cause for the spikes ![image](https://europe1.discourse-cdn.com/flex017/uploads/prometheus/original/1X/6ba1f3af11b08c4f576a33fe01e73016f0a99b49.png) ---
**Author:** ![SuperQ](https://dub1.discourse-cdn.com/flex017/user_avatar/discuss.prometheus.io/superq/32/4_2.png) [@SuperQ](https://discuss.prometheus.io/u/SuperQ)\ **Post date:** [December 7, 2021, 10:30am UTC](https://discuss.prometheus.io/t/rate-calculation-results-in-hugely-unexpected-exponential-values/621/2 "2021-12-07T10:30:51Z")
You likely have a small counter value drop, which is resulting in `rate()` thinking you have a counter reset. This single errant sample is the problem. If you query `api_heartbeat_seconds_bucket{le="1.0",instance="SITE-A:1234"}[10m]` with an instant query (table view in the UI), it will return the actual samples and timestamps for debugging. As for why you are getting this, I don’t know. ---
**Author:** ![akikul](https://dub1.discourse-cdn.com/flex017/user_avatar/discuss.prometheus.io/akikul/32/285_2.png) [@akikul](https://discuss.prometheus.io/u/akikul)\ **Post date:** [January 19, 2022, 2:40pm UTC](https://discuss.prometheus.io/t/rate-calculation-results-in-hugely-unexpected-exponential-values/621/3 "2022-01-19T14:40:54Z")
Thanks for the tip. Here is what I have got: ```auto 1856408410 @1637544666.282 1856437290 @1637544726.281 1856437290 @1637544726.282 1856466156 @1637544786.281 1856466155 @1637544786.282 1856494989 @1637544846.281 1856494989 @1637544846.282 1856523850 @1637544906.281 1856523850 @1637544906.282 1856552706 @1637544966.281 1856552705 @1637544966.282 1856581550 @1637545026.281 1856581548 @1637545026.282 1856610432 @1637545086.282 1856639309 @1637545146.281 1856639310 @1637545146.282 1856668165 @1637545206.282 1856697018 @1637545266.282 1856725885 @1637545326.282 1856754720 @1637545386.282 1856783600 @1637545446.282 1856812474 @1637545506.282 1856841370 @1637545566.281 1856841370 @1637545566.282 1856870286 @1637545626.281 1856870286 @1637545626.282 1856899171 @1637545686.281 1856899171 @1637545686.282 1856928067 @1637545746.281 1856928067 @1637545746.282 1856956962 @1637545806.282 1856985867 @1637545866.282 1857014787 @1637545926.282 1857043694 @1637545986.282 1857072573 @1637546046.282 1857101486 @1637546106.282 1857130313 @1637546166.281 1857130315 @1637546166.282 1857159196 @1637546226.281 1857159198 @1637546226.282 1857188104 @1637546286.282 1857216986 @1637546346.281 1857216986 @1637546346.282 1857245861 @1637546406.282 1857274774 @1637546466.282 1857303602 @1637546526.281 1857303602 @1637546526.282 1857332498 @1637546586.281 1857332499 @1637546586.282 1857361384 @1637546646.282 1857390280 @1637546706.282 1857419175 @1637546766.282 1857448064 @1637546826.281 1857448064 @1637546826.282 1857476776 @1637546886.281 1857476776 @1637546886.282 1857505645 @1637546946.282 1857534527 @1637547006.282 1857563409 @1637547066.282 1857592243 @1637547126.282 1857621083 @1637547186.281 1857621083 @1637547186.282 1857649933 @1637547246.282 1857678817 @1637547306.282 1857707733 @1637547366.281 1857707733 @1637547366.282 1857736628 @1637547426.281 1857736628 @1637547426.282 1857765509 @1637547486.281 1857765509 @1637547486.282 1857794348 @1637547546.282 1857823177 @1637547606.281 1857823177 @1637547606.282 1857852032 @1637547666.282 1857880902 @1637547726.282 1857909756 @1637547786.282 1857938611 @1637547846.282 1857938610 @1637547846.286 1857967502 @1637547906.282 1857996367 @1637547966.282 1858025273 @1637548026.282 1858054149 @1637548086.282 1858083041 @1637548146.281 1858083041 @1637548146.282 1858111935 @1637548206.282 ``` ---
**Author:** ![akikul](https://dub1.discourse-cdn.com/flex017/user_avatar/discuss.prometheus.io/akikul/32/285_2.png) [@akikul](https://discuss.prometheus.io/u/akikul)\ **Post date:** [February 10, 2022, 1:42pm UTC](https://discuss.prometheus.io/t/rate-calculation-results-in-hugely-unexpected-exponential-values/621/4 "2022-02-10T13:42:22Z")
I was hoping if there was a way to confirm the behaviour I was seeing that would be great. Not sure if @SuperQ would be able to help. Thanks in advance