Use Histogram, not Summary, in WAI #18
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Brings us in line with Prometheus best practices: https://prometheus.io/docs/practices/naming/#metric-names
https://prometheus.io/docs/practices/histograms/ has a full discussion, but the gist is that histograms can be aggregated across processes whereas summaries cannot. This makes histograms more useful in environments where there is more than one process handling web requests, which is perhaps the more common case.
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Test failure looks like an unrelated intermittent failure due to summary approximation. |
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Agreed, the summary tests are unfortunately a bit flaky :( |
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Just pushed v0.2.0 with these changes. Thanks for all the contributions! |
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Tiny follow-on from #17, but logically independent. Probably shouldn't be reviewed until after #16 and #17.
Uses Histograms, not Summary, in WAI, which allows metrics gathered from multiple processes to be aggregated meaningfully.
This is kind of a breaking change, as queries that work on summaries don't work on histograms. I suggest combining this change with #17 in a release, so that at least at the PromQL level, we change a name at the same time as changing the semantics.
Full discussion of summaries vs histograms at https://prometheus.io/docs/practices/histograms/