I’m trying to work out how to subtract one singlestat value from another, to display the difference as a third value.
What I’m aiming for is a way to show 6 different singlestat values, each one showing the sum of a measurement for “yesterday”, “the day before yesterday”, “the day before that” and so on.
I’ve figured out that I can use Grafana’s “Time range” tab in the query builder to get the sum for yesterday with an “override” of “now/d” and a “time shift” of “1d”. I can’t figure out how to get the day before yesterday, but I can get both added together with an “override” of “now/d” and a “time shift” of “2d”, so if I can subtract the first calculated value from the second one, that will give me the answer I want, for the day before yesterday.
And so on.
I’ve tried an “override” of “now-1d/d” and “now/d-1d” but these get deleted and reset to empty.
I’m using InfluxDB as the data source, so I know that I can’t do any maths operations such as % (remainder) on time values, so I don’t think there’s any way of getting “the start of yesterday” and “the end of yesterday” into a query statement…
Does anyone have any ideas or solutions to this problem?
Thanks for the comment, but I don’t understand what you’re suggesting I should
put into my Grafana query in order to get the value for “the day before
yesterday”.
In fact I just figured it out, and wow is this obscure!
To show the value for “today so far” you use “override relative time” =
“now/d” and leave “add time shift” blank. So far so good.
To show the value for “yesterday” (midnight to midnight) you use “override
relative time” = “now/d” and set “add time shift” to “1d/d”.
For “the day before yesterday” you use “override relative time” = “now/d” and
set add time shift" to “2d/d”, and so on.
I had tried setting the time shift to “1d”, “2d” etc, but it hadn’t for a
moment occurred to me that the syntax might be “2d/d”. I’ve never seen
anything quite like that in another language, and whereas I’m pretty sure that Manage dashboards | Grafana documentation is the right place in the
documentation to look for this stuff, it doesn’t say anything about this
syntax.
Incidentally, I got the clue about how to do this from
If anyone who actually knows how this syntax works (I mean, “1w/d” seems to do
something, and so does “1d/w”, but I have no idea what the background meaning
of those might be) could update the documentation to explain it, I think it
might enable a lot more people to use this very useful (in certain situations)
feature.
