dashboard: interval and interval_ms has different values, when min-interval is involved

[gabor]

in a dashboard, let's say you set the min-interval to 70s, and choose a time-range of 30 minutes:

• the variable $__interval will be 1m
• the variable $__interval_ms will be 70000

in other words, $__interval is rounded to a "nice" number, but $__interval_ms is kept at the "exact" value.

the problem is in this code: https://github.com/grafana/grafana/blob/main/packages/grafana-data/src/datetime/rangeutil.ts#L288-L291 , as you see intervalMs is taken as-is, but the interval value goes through some "rounding".

please note, this problem only happens when min-interval is involved, because if there is no min-interval, the intervalMs calculated at https://github.com/grafana/grafana/blob/main/packages/grafana-data/src/datetime/rangeutil.ts#L284 is also rounded, so in a way, when there is no min-interval:

• intervalMs is rounded once
• interval is rounded two times with slightly different rules, which will usually keep it the same as the single-rounded intervalMs (still, this is quite fragile, i'd recommend not relying on this fact)

the documentation for $__interval_ms says: "This variable is the $interval variable in milliseconds" ( https://grafana.com/docs/grafana/latest/variables/variable-types/global-variables/#interval_ms ). that is not correct currently.

NOTE: there is also the additional problem, that, we specified a min-interval of 70s, and the interval becomes 1m, which is lower than the requested min-interval.

[gabor]

i found some additional info that i added to the issue (the fact that this happens only when min-interval is involved)

[github-actions[bot]]

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[gabor]

(seems this never got assigned to a squad, i assigned it to plugins-platform, as they own rangeUtil.ts, feel free to assign it to a better owner, thanks!)