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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-04 14:31:17 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-04 14:31:17 +0000 |
commit | 8020f71afd34d7696d7933659df2d763ab05542f (patch) | |
tree | 2fdf1b5447ffd8bdd61e702ca183e814afdcb4fc /web/api/queries/median/README.md | |
parent | Initial commit. (diff) | |
download | netdata-8020f71afd34d7696d7933659df2d763ab05542f.tar.xz netdata-8020f71afd34d7696d7933659df2d763ab05542f.zip |
Adding upstream version 1.37.1.upstream/1.37.1upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'web/api/queries/median/README.md')
-rw-r--r-- | web/api/queries/median/README.md | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/web/api/queries/median/README.md b/web/api/queries/median/README.md new file mode 100644 index 0000000..5600284 --- /dev/null +++ b/web/api/queries/median/README.md @@ -0,0 +1,60 @@ +<!-- +title: "Median" +description: "Use median in API queries and health entities to find the 'middle' value from a sample, eliminating any unwanted spikes in the returned metrics." +custom_edit_url: https://github.com/netdata/netdata/edit/master/web/api/queries/median/README.md +--> + +# Median + +The median is the value separating the higher half from the lower half of a data sample +(a population or a probability distribution). For a data set, it may be thought of as the +"middle" value. + +`median` is not an accurate average. However, it eliminates all spikes, by sorting +all the values in a period, and selecting the value in the middle of the sorted array. + +Netdata also supports `trimmed-median`, which trims a percentage of the smaller and bigger values prior to finding the +median. The following `trimmed-median` functions are defined: + +- `trimmed-median1` +- `trimmed-median2` +- `trimmed-median3` +- `trimmed-median5` +- `trimmed-median10` +- `trimmed-median15` +- `trimmed-median20` +- `trimmed-median25` + +The function `trimmed-median` is an alias for `trimmed-median5`. + +## how to use + +Use it in alarms like this: + +``` + alarm: my_alarm + on: my_chart +lookup: median -1m unaligned of my_dimension + warn: $this > 1000 +``` + +`median` does not change the units. For example, if the chart units is `requests/sec`, the result +will be again expressed in the same units. + +It can also be used in APIs and badges as `&group=median` in the URL. Additionally, a percentage may be given with +`&group_options=` to trim all small and big values before finding the median. + +## Examples + +Examining last 1 minute `successful` web server responses: + +- ![](https://registry.my-netdata.io/api/v1/badge.svg?chart=web_log_nginx.response_statuses&options=unaligned&dimensions=success&group=min&after=-60&label=min) +- ![](https://registry.my-netdata.io/api/v1/badge.svg?chart=web_log_nginx.response_statuses&options=unaligned&dimensions=success&group=average&after=-60&label=average) +- ![](https://registry.my-netdata.io/api/v1/badge.svg?chart=web_log_nginx.response_statuses&options=unaligned&dimensions=success&group=median&after=-60&label=median&value_color=orange) +- ![](https://registry.my-netdata.io/api/v1/badge.svg?chart=web_log_nginx.response_statuses&options=unaligned&dimensions=success&group=max&after=-60&label=max) + +## References + +- <https://en.wikipedia.org/wiki/Median>. + + |