…ions

Support using WITH template vars in the following places where duration can be passed:

- Lookbehind windows in square brackets: `with (w=5m) m[w]` is transformed to `m[5m]`
- Steps in square brackets: `with (step=5m) m[1h:step]` is transformed to `m[1h:5m]`
- Offsets: `with (off=5m) m offset off` is transformed to `m offset 5m`

Updates VictoriaMetrics/VictoriaMetrics#4025
Updates #12

Thanks to @lujiajing1126 for the initial implementation at #13

Note that this feature doesn't allow specifying dynamic durations in the following way:

  with (w = ((day_of_month()-1) * 24 + hour()) + "h") m[w]

It allows using only static durations

Support for dynamic durations requires significant refactoring of the code responsible for calculating rollups in `/api/v1/query_range` handler.
It will be needed to use different lookbehind windows per each calculated data point per each `step`. Currently the code assumes
that the lookbehind window is static across every calculated data point.

…0.61.1

This adds support for passing durations via WITH template vars:

- `WITH (w = 5m) m[w]` is transformed to `m[5m]`
- `WITH (f(w, step, off) = m[w:step] offset off) f(5m, 10s, 1h)` is transformed to `m[5m:10s] offset 1h`

Updates #4025
Updates VictoriaMetrics/metricsql#12

See also the initial implementation by @lujiajing1126 at VictoriaMetrics/metricsql#13

…0.61.1

This adds support for passing durations via WITH template vars:

- `WITH (w = 5m) m[w]` is transformed to `m[5m]`
- `WITH (f(w, step, off) = m[w:step] offset off) f(5m, 10s, 1h)` is transformed to `m[5m:10s] offset 1h`

Updates #4025
Updates VictoriaMetrics/metricsql#12

See also the initial implementation by @lujiajing1126 at VictoriaMetrics/metricsql#13