
Practical Introduction to Prometheus for Developers - melzarei
https://github.com/danielfm/prometheus-for-developers
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personomas
> the second is how the 99th percentile reported by the the summary (1s) is
> quite different than the one estimated by the histogram_quantile() function
> (~2.2s). How can this be?

> ... for the quantile estimation from the buckets of a histogram to be
> accurate, we need to be careful when choosing the bucket layout; if it
> doesn't match the range and distribution of the actual observed durations,
> you will get inaccurate quantiles as a result.

> According to the previous plot, all slow requests from our application are
> falling into the 1s-2.5s bucket, resulting in this loss of precision when
> calculating the 99th percentile.

Can anyone explain mathematically why this is happening? I think I understand
conceptually, but if I could also perhaps understand it from a mathematical
perspective, I would feel much more confident!

By the way, I think it's a great introduction!

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collyw
Good timing, I just started working with Prometheus this week.

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machawinka
Well written.

