Is a percentile line calculated from history data or trend data?

[kinu]

I've configured an item as below and would like to know if history data or trend data is used to calculate a percentile line.



(1) If a x axis shows 90 days, is a percentile line calculated from history data, which means every 1 minute data?
(2) If a x axis shows 180 days, is a percentile line calculated from both history data and trend data, which means every 1 minute data for last 90 days and every 1 hour data for days before that?
And which data (min, avg, max) is used for the trend data?

Thanks advance for your help!

[Brambo]

I wonder if you can see 90* 1440 datapoints in a graph visually... When I look at a few graphs from my own system.
When you are in the history window you can view all history points when zooming in on the data. When you are out of the history window trend data is shown, which contains (on hourly basis) min, max and average value.

[kinu]

Thank you for your comment.

Do you mean that it depends on how the graph is visualized on a display?
I assume that the data is stored in a Zabbix and used for percentile calculation.
(Because the "History storage period" is "90d" in this case, I assume all (1440) data for last 90 days are stored and can be used.)

[Brambo]

In the last 90 days period you can zoom in more detail on graphs because of the 1 minute interval data point (if you didn't set discard with heartbeat on the item to reduces duplicate values in a row )
When you want to visualize data of days 80 - 180 than a graph is shown. But when you zoom in on the data older than 90 days only trend data points can be used. (average, min, max)

[kinu]

Ah, I understood what you meant.
Yes, I know the history data is kept for 90 days and older data is kept as the trend data.

What I'd like to know is how percentile line is caluculated.

(1) If a x axis shows 90 days, is a percentile line calculated from history data, which means every 1 minute data?
(2) If a x axis shows 180 days, is a percentile line calculated from both history data and trend data, which means every 1 minute data for last 90 days and every 1 hour data for days before that?
And which data (min, avg, max) is used for the trend data?

[moooola]

I think the percentile calculation is done dynamically using the values currently displayed on the graph.
Whether history or trend is used for graphs seems to depend on the amount of data to be displayed.

https://www.zabbix.com/documentation/current/en/manual/web_interface/frontend_sections/dashboards/widgets/graph

https://www.zabbix.com/documentation/current/en/manual/config/visualization/graphs/simple#generating-from-historytrends

I set the time width to the limit and confirmed how changing the time width by 1 second switches between using history data and using trend data.

[now-219825s to now]


[now-219826s to now]


Although the time axis is 1 second apart, the percentile differs between 6.6944% and 6.8654% depending on the displayed data.

In my test environment, there was not much data accumulated, so I was unable to verify how it behaves at the last 90 days of the historical data retention period. sorry.

[kinu]

Thank you for checking the behavour on your side, moooola.

Though the difference between [now-219825s to now] and [now-219826s to now] is only 1 second, the x axis value of [now-219826s to now] seems wider.
Doesn't the difference between the value of percentiles come from the difference of x axis ranges?