# Graphing aggregation difference in Kibana
**URL:** https://discuss.elastic.co/t/graphing-aggregation-difference-in-kibana/169160
**Category:** Kibana
**Created:** [February 20, 2019, 8:18am UTC](https://discuss.elastic.co/t/graphing-aggregation-difference-in-kibana/169160 "2019-02-20T08:18:26Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@Jetze\_Schaafsma](https://discuss.elastic.co/u/Jetze_Schaafsma)
#### Post date: [February 20, 2019, 8:18am UTC](https://discuss.elastic.co/t/graphing-aggregation-difference-in-kibana/169160/1 "2019-02-20T08:18:26Z")
I have 'start' and 'end' events (so, separate documents in my 'events' index) for doing work.
I don't really care about how often I start or stop; I particularly care about their difference!
Now, as a hack, I could do ugly things like using +1 for start, and -1 for end, and aggregate over the sum, but I don't want to do that.
I understand from this thread ([How to find the difference of two metric aggregations in kibana](https://discuss.elastic.co/t/how-to-find-the-difference-of-two-metric-aggregations-in-kibana/27579)) that it wasn't possible in the past. Did anything change in the mean time? Is this coming in the near future?
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### Author:  [@lukas](https://discuss.elastic.co/u/lukas)
#### Post date: [February 20, 2019, 8:40pm UTC](https://discuss.elastic.co/t/graphing-aggregation-difference-in-kibana/169160/2 "2019-02-20T20:40:56Z")
There isn't really a great way to accomplish this in Kibana as there is no concept of "joining" documents based on a key. What you might consider doing instead is calculating the difference when indexing the "stop" document and adding it as a separate field (`millis_elapsed` or something).
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### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [March 20, 2019, 8:41pm UTC](https://discuss.elastic.co/t/graphing-aggregation-difference-in-kibana/169160/3 "2019-03-20T20:41:02Z")
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