Broken graph when using "Offset series time by" on TSVB with series Stacked

[Kilhog]

Kibana version: 7.15.2
Elasticsearch version: 7.15.2
Server OS version: Latest Docker
Browser version: Safari
Browser OS version: 15.1
Original install method (e.g. download page, yum, from source, etc.): Docker
Describe the bug:

When I try do make a TSBV with my current data on 1 year (01/01/2021 - 16/12/2021), and add a second series on the same graph with the same parameters except the "Offset series time by" set to 1y, I have a weird behaviour. The line of the first series (without time shift) have gap after the date of the time change (summer / winter time), but I can still view the data with the "popover dialog"

Steps to reproduce:

1. Create TSVB with a first series (cumulative sum, grouped by terms, with Chart type: line and Stacked: stacked)
2. Create a second series (cumulative sum with no grouped by, with Chart type: line and Stacked: none and time shift 1y)
3. Use time range from 01/01 to 16/12
4. Offset the second series by 1 year

PS : I will explain in a futur issue why a choose time range 01/01 to 16/12 and not 01/01 to 31/12, there is a another bug involved. I try to break down the problem report in #120441

Expected behavior:

Chart line with no gap

Screenshot:

Graph bug :

First series configuration :

Second series configuration :

Winter / Summer time change in France :

[elasticmachine]

Pinging @elastic/kibana-vis-editors @elastic/kibana-vis-editors-external (Team:VisEditors)

[stratoula]

@Kilhog thanx a lot for submitting this. Can you please check if the gaps are gone when you turn to Yes the Ignore daylight time setting? You can find it on the Panel options tab

[Kilhog]

@stratoula same behaviour with "Ignore daylight time" to true

[stratoula]

Thank you, we will look into this :) cc @alexwizp

[stratoula]

@Kilhog we managed to replicate it. We will try to apply a fix in a future version.
I could propose though to use Lens instead of TSVB.

It seems that the bug is not present there and judging from your TSVB configuration, you can re-create it in Lens.

Lens support timeshift and cumulative sum.

This is an example of how you can configure it in Lens. I added two layers (one area stacked and one normal). The first layer is using cumulative sum, the second one is using average but you can use whatever metric you want. It is shifted by 1 year.

About the TSVB bug, we investigated it with @flash1293

• The problem is in this file

  kibana/src/plugins/vis_types/timeseries/server/lib/vis_data/response_processors/series/time_shift.js

  Line 24 in 60500c2

  moment.utc(row[0]).add(offsetValue, offsetUnit).valueOf(),

  
  We are using utc and not the correct timezone, this is the reason we see these discrepancies.
• We should get the request timezone, set it on this file and then set it back to the previous value

[stratoula]

An update here for whoever would like to take it.
The problem is the utc used here

kibana/src/plugins/vis_types/timeseries/server/lib/vis_data/response_processors/series/time_shift.js

Line 24 in 60500c2

moment.utc(row[0]).add(offsetValue, offsetUnit).valueOf(),

as I mentioned above.

If you remove the utc, the bug is fixed but unfortunately it creates another bug. It doesn't work fine with the fix that was applied here #98484

To be more specific, I have 3 points, on 27, 28 and 29 of March 2020. I shift them 1y. (28 of march happens the DST in greece). So with removing the utc, the Ignore daylight switch doesnt work correctly. Here in the screenshot it should show 5:00 but it shows 4:00 instead. So we should ensure that both things work correctly.

Note: I also tried to fetch the timezone from the request, set it on the timeshift and then set it to its previous value but this also doesn't solve the problem

[flash1293]

As discussed, this is how we can align this (and fix the bug discovered during investigation):

• Use moment in the right time zone in the time_shift response processor linked above as described by Stratoula
• If "Ignore daylight time" is set to true, switch back to moment.utc in the time_shift processor and also disable the new time axis (as this feature is not compatible)