[TSVB] Math params._interval is incorrect when using entire timerange mode

[wylieconlon]

params._interval is used to normalize the display of values, for example to get an average rate per second. When using the entire timerange mode, it should represent the total number of milliseconds in the time range.

Steps to reproduce:

1. Open TSVB and add a Math function. Type params._interval into the math input.
2. Switch to the Metric visualization type.
3. Open Panel Options, then choose "Last value" timerange mode instead. Notice that the interval is the same.

Expected behavior: The params._interval is set to the number of milliseconds in the query, the to - from time.

With entire time range:

With last value mode:

[elasticmachine]

Pinging @elastic/kibana-app (Team:KibanaApp)

[alexwizp]

Thank you @wylieconlon . This is definitely wrong

[bvader]

@alexwizp @wylieconlon

This Also Appears to Affect the Overall Metric Calculation Too.

I have validated that this DID work in 7.11.1 but does not in 7.12.x so it looks like a regression
EDIT : Now I am not sure this did work in 7.11

See Below Timeseries

Then The Metrics with Last Bucket is correct

But clearly the Entire Time Range is not working as the Average should be about 400

[bvader]

@alexwizp @wylieconlon

Perhaps @simianhacker has a perspective.

Another point of reference when the data is NOT a Series Agg, the Last Value vs Entire Time Range works for the metric
In other words for a single series it seems to works See Below

So it looks like perhaps it is related to the Series Agg

With Last Value ... Yup About 4.8

Now with Entire Range Yup about 1.6

[alexwizp]

@bvader, thanks. I created a new issue based on your comment because I'm not sure if this issue is related to the original one. But thank you very much for this case, we will see it.

[simianhacker]

@wylieconlon "Entire time range" mode didn't exist when I was actively working on TSVB. Just looking at the series_agg code, nothing stands out to me as long as the aggregation response is in the right format, it should work with one bucket just as well as many.