1328678 - Aggregator should have more buckets for count histograms

Status: RESOLVED WONTFIX

(Data Platform and Tools :: General, defect, P3)

Description

[Frank Bertsch [:frank]]

For some count histograms, most counts are beyond 10000 [0]. We need to continue to have bucket for 10000 histograms or more [1]. My idea would be linear histograms for the first 25 or so, then calculated exponential for the rest, tacking on new buckets when we need them. This would allow differentiation far beyond 10000, while still keeping precision for low counts.

The big issue would be backfill. We could either do an actual backfill on a few recent count histograms (such as the one mentioned), or include some sort of note on TMO to let people know the difference.

[0] https://mzl.la/2jamLUb
[1] https://github.com/mozilla/python_mozaggregator/blob/master/mozaggregator/aggregator.py#L16

Comment 1

[Roberto Agostino Vitillo (:rvitillo)]

Variations of this issue show up time and time again; we should consider the use of histograms with dynamic range (e.g. [1][2]) to solve this class of problems.

[1] https://github.com/HdrHistogram/HdrHistogram
[2] https://github.com/vitillo/lua_tdigest

Comment 2

[:Harald Kirschner :digitarald]

Any action here? This skews one of Quantum engagement metrics. If we collect data and then make it less useful in aggregation; we can stop collecting the data and save the bandwidth/storage

Comment 3

[Frank Bertsch [:frank]]

(In reply to :Harald Kirschner :digitarald from comment #2)
> Any action here? This skews one of Quantum engagement metrics. If we collect
> data and then make it less useful in aggregation; we can stop collecting the
> data and save the bandwidth/storage

If this is blocking Quantum work we can certainly move it up the priority queue.

Question: How and why are you using aggregates data for engagement measures? Are you using the data to create a dash somewhere? Or is this just for viewing in TMO?

Comment 4

[:Harald Kirschner :digitarald]

We are planning to use scroll engagement as proxy for improved performance in pref-flipping experiments.

Comment 5

[Frank Bertsch [:frank]]

Is this usage then predicated on bug 1336989? Do you also need to see experiments and branches?

Comment 6

[:Harald Kirschner :digitarald]

if experiments means the pref-flipping experiment pipeline, then yes.