TSVB - timeseries graph stacking doesn't work when using calculation with negative values are filtered by terms

[nich07as]

Kibana version: 6.0.1

Elasticsearch version: 6.0.1

Server OS version: Centos7

Browser version: Chrome

Browser OS version: MacOS Sierra

Original install method (e.g. download page, yum, from source, etc.): yum

Description of the problem including expected versus actual behavior:
The TSVB when drawing a graph on negative values; i.e. using calculation with params *-1; then filtered by terms; and the stack option is used; the value computation does not seem to honor the calculations.

Steps to reproduce:

1. Create 2 series; first --> one positive value graph filtered by terms (any terms) with Top 2
2. Create the second series --> negative value graph by calculate function with parameter named y; params.y > 0 ? params.y * -1 : 0 then filtered by terms (any terms) Top 2
3. Observe the current graph; then change the series options to stacked; you'd see the numbers skewed towards positive.

Errors in browser console (if relevant): No errors but visuals are presenting data that's somewhat skewed.

Provide logs and/or server output (if relevant): No error.

[sio4]

Hi all,
Actually this issue was created by @nich07as after my question to him at Elastic On Seoul, anyway I need to explain some details and my opinion on this issue.

First, I think it is not a bug and all values are used for aggregation. (stacking, of lines) Anyway, it looks like negative, calculated, values are ignored; but in fact, the values are added to (stacked over) positive high values (so just the results are nearly 0, so no negative lines are there.)

See attached images:

: original graph with stack option "none"

: just "stacked" option for negative values --> it works as shown. (growth of negative area)

: "stacked" options for all series --> see darker shadow on area. it means, line and area for negative value covers positive lines and areas of stacking.

Yes, the final value of summation, means stacked, is near by zero. since the positive value and negative value on same document are mostly same length with different direction.

So negative value itself is working for stacking.

[sio4]

It's NOT a bug, anyway what I want to say is, and my feature request for this issue is:

I think we need some additional key for the stacking group.
I mean it is not positive to positive and negative to negative summation. I (maybe we) need to select stacking group so we can add (stack) line A and B as AB which has height of A+B, by tagging A and B as stacking group "ab", but C and D should not added to AB, but there is another stacking group CD with height of C+D, generated by tagging C and D as stacking group "cd". show my drawing:

Just separated group of stacking, and the key(name) of the stacking group. it makes us can draw this kind of graph on the same page(graph). (in my case, they are RX and TX of ports on network switch)

Sorry for my poor English, anyway the graph and drawing show something. :-)

[nich07as]

@sio4 - I believe the values are correct but when stacking the charts; the plots are somewhat skewed. Just to clarify.

[sio4]

@nich07as see second graph. It shows stacking of negative values only and works well. And on 3rd graph, you can see dark purple area. It was generated with overwrapped blue area of negative values over existing red area of positive values. Means, stacking as up-up-down-down not up-up-up-up. So it is normal and works well with those data set.

The problem is we cannot just separate them as two sets of stacking. As RXs are on one group, TXs are on second group.

[sio4]

Since my expression in English is not enough, I draw some lines on the graph.

Stacking itself are working fine. but RXs are merged with TXs.

[sidharthvijayakumar]

Do we have this feature in Kibana? I wanted to stack -ve values on the -ve Y-axis (4th quadrant ) but does not work