docs/Cluster-VictoriaMetrics.md: clarify the description on why -dosnwampling.period must be set at both vmstorage and vmselect

This is a follow-up for ca7457d906
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Aliaksandr Valialkin 2023-10-31 16:53:44 +01:00
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@ -750,12 +750,15 @@ See how to request a free trial license [here](https://victoriametrics.com/produ
## Downsampling
[Downsampling](https://docs.victoriametrics.com/#downsampling) is available in [enterprise version of VictoriaMetrics](https://docs.victoriametrics.com/enterprise.html).
It is configured with `-downsampling.period` command-line flag. The same flag value must be passed to both `vmstorage`
and `vmselect` nodes. Configuring `vmselect` node with `-downsampling.period` command-line flag makes query results more
consistent, as `vmselect` will evenly downsample all received data samples if requested time range will intersect with configured
`-downsampling.period`. For example, if `-downsampling.period=30d:5m` and user requests `60d` of data then vmselect will downsample
all datapoints (newer and older than `30d`) to `5m` intervals. If this flag is omitted for `vmselect`,
Downsampling is available in [enterprise version of VictoriaMetrics](https://docs.victoriametrics.com/enterprise.html).
It is configured with `-downsampling.period` command-line flag according to [these docs](https://docs.victoriametrics.com/#downsampling).
The same flag value must be passed to both `vmstorage` and `vmselect` nodes. Configuring `vmselect` node with `-downsampling.period`
command-line flag makes query results more consistent, because `vmselect` uses the maximum configured downsampling interval
on the requested time range if this time range covers multiple downsampling levels.
For example, if `-downsampling.period=30d:5m` and the query requests the last 60 days of data, then `vmselect`
downsamples all the [raw samples](https://docs.victoriametrics.com/keyConcepts.html#raw-samples) on the requested time range
using 5 minute interval. If `-downsampling.period` command-line flag isn't set at `vmselect`,
then query results can be less consistent because of mixing raw and downsampled data.
Enterprise binaries can be downloaded and evaluated for free from [the releases page](https://github.com/VictoriaMetrics/VictoriaMetrics/releases/latest).