Although Wavefront accepts and stores data at up to 1 second resolution, Wavefront charts display that granularity only for small time windows on high resolution displays. In most cases, Wavefront groups data points into time interval buckets and the buckets are mapped to display points. Wavefront lets you select a summarization method for grouping (or summarizing) points into buckets.
Chart resolution is the bucket time interval and it displays in the Horizontal Scale field in the lower-left corner of a chart. The following chart has 240 point buckets and the resolution of each bucket is 30 sec. If the source is sending 1 point per second, each bucket summarizes 30 points. On the other hand, if the source is sending 1 point every minute, no summarization occurs. If you choose the Count summarization method you can see how many points are in each bucket.
Factors Affecting Chart Resolution
Chart resolution is determined by two factors: chart time window and dedicated display resolution. Consider the following chart time window and display resolution examples and the bucket size they would typically have:
10 minute time window + 1280px display = ~1 second buckets (best resolution) 8 day time window + 3840px display = ~30 minute buckets (second best resolution) 8 day time window + 1280px display = ~60 minute buckets (third best resolution)
You can see that larger time windows and lower display resolutions each result in progressively lower chart resolution.
Here is a series of charts with increasing time window for the same display resolution (1280px). When the time window increases from 10 minutes to 2 hours (12 fold), the bucket size increases proportionately from 1 sec to 12 sec and the number of buckets remains the same, but when the time window increases from 2 to 6 hours (3 fold), the bucket intervals increase from 12 to 60 sec (5 fold) and the number of buckets is reduced proportionately: 600 * 3/5 = 360.
10-minute window: 600 point buckets across, with ~1 sec buckets
2-hour window: 600 point buckets across, with ~12 sec buckets
6-hour window: 360 point buckets across, with ~60 sec buckets.
Here’s video that demonstrates resolution and summarization options and use cases:
The align() Function and Resolution
align() function lets you specify the size of the buckets—45 minute, 2 hour, 1 day, etc.—into which the points are grouped. However, the supported chart resolution is the most granular view you can get. Therefore, for the 1-week time window + 3840px screen example, specifying
align(15m,...) would not result in 15 minute buckets being displayed on the screen due to the ~30 minute buckets already associated with the chart. If you were to use the
align() function, Wavefront would first align the values into 15 minute buckets and then take two aligned values and summarize those based on the Summarize By method.