[Logs UI] navigation via the minichart is confusing

[katrin-freihofner]

This came up when building kibana master locally (using the shared dev cluster).

Browser version:
Chrome Version 77.0.3865.90 (Official Build) (64-bit)

Browser OS version:
Mac

Describe the bug:
When clicking on a specific time in the mini-chart (6am and 9am) as a user, I suppose the stream would show me log lines from this time. But the timestamp of the log lines that show up is a different one. Additionally, the minichart also moves, which I haven't expected.

Expected behavior:
When clicking on a time, log lines with the appropriate timestamp show up. The minichart does not move at all.

[elasticmachine]

Pinging @elastic/logs-metrics-ui (Team:logs-metrics-ui)

[Zacqary]

Two issues here:

1. When the log minimap is working correctly, we need to change UX so that we don't move it when the user clicks on a new time. Only move it when the user scrolls up and down.
2. The request to get new logs centered around the timestamp where the user clicks still isn't always working correctly

I'd thought issue 2 was only happening when trying to click on a point where there were no logs, but the gif clearly shows the user clicking on a place where there's a significant enough log density to jump to that section.

Perhaps related, when checking to confirm this behavior on my local machine, I ran into this:

Note that there are no logs past October 18th, but because I'm looking at the UI on October 21st it's still rendering a completely blank minimap. Not sure if that's the same underlying cause but it's something to note

[Zacqary]

So for some reason the getYScale function returns inaccurate results on page load, and only becomes accurate again after you click and drag the log minimap. Trying to find out why. It might be related to the way target is handled; this is supposed to represent the midpoint of the displayed logs on screen, but sometimes it doesn't if logs aren't dense enough to get results at that exact midpoint.

[Zacqary]

#48826 fixes issue 2 from my above summary.

[Zacqary]

Some further commentary on the UX portion of this issue:

• When clicking on a time, log lines with the appropriate timestamp show up is a bug, fixed by [Logs UI] Fix initial accuracy of logs minimap click #48826
• The minichart does not move at all would be an enhancement

Currently, the log minimap will re-render every time the target (current timestamp) changes, so that the center of the minimap roughly corresponds to the center of the displayed logs. For example:

The blue line on the minimap is pointing to 06:00:36.839.

This expected behavior is asking us to break from this convention. For instance, if I clicked on 3 AM, we would want to freeze the minimap in place and move the blue line up to around 3 AM.

I like this idea and I agree it would reduce confusion, but I think it begs some additional questions:

• Does the minimap still move when the user scrolls up and down, or does it also stay frozen?
• If it stays frozen, what happens when the user scrolls all the way to the top or bottom edge of the minimap? Do we then scroll the minimap, or do we have it jump an entire screen?
• If we're no longer tying the minimap to the center of the scroll panel, how do we decide what portion of the minimap initially renders?

@hbharding tagging you on this since we need UX input

[katrin-freihofner]

• Does the minimap still move when the user scrolls up and down, or does it also stay frozen?

It stays frozen

• If it stays frozen, what happens when the user scrolls all the way to the top or bottom edge of the minimap? Do we then scroll the minimap, or do we have it jump an entire screen?

The minimap gets scales to show the extended timeframe.

• If we're no longer tying the minimap to the center of the scroll panel, how do we decide what portion of the minimap initially renders?

The timeframe that is selected in the datepicker. And in case of live streaming we have to pick a start time (for example now - 2 h).

[weltenwort]

I think most of these problems will be dealt with via #49154. The mini-map will show exactly the date range selected in the time picker and clicking will jump to the location. The interval visible in the stream to the right will continue to be shown as a highlighted window, but it won't always be centered anymore.

[Zacqary]

@katrin-freihofner Since the bug portion of this ticket is fixed should we move over to #49154 for the UX changes? Or are these still in their own scope do you think?

[katrin-freihofner]

@Zacqary yes, I think it works much better now.