Expression query in Stat panel issue

Hi,

I saw this Expression query in Stat panel

which talks about expression query in Stat panel.

And I’m doing almost the same case with using Expression function.

My data source is from Cloudwatch and I need to calculate the success rate of invoking API, so I had two queries, one was the number of calling API, and the other was the number of successfully executing the API, therefore I used Expression function to division two numbers to calculate the successful rate.

but there’s the problem, my two queries refId were named A and B, so I wrote “$B/$A*100” and it was not work, even I wrote only ‘$A’ it was wrong either.

I’ve followed the official document->About expressions | Grafana documentation

But I couldn’t figure out why It was wrong!


This pic shows that only two queries are work!


You can see the pic above and it occurred error when I add new Expression.

Is syntax like “$B/$A*100” wrong? Or it can’t get the value of refId A and refId B?

Your expression C looks fine, but I noticed that in my screenshot (Grafana 9.0.7), it says
C (Expression)
while yours says
C (_expr_)

What version of Grafana are you using? Are you certain that the values returned in A and B are integers or floats (and not strings)?

1 Like

Hi sir, thanks for your reply.

I thought the cases between us were different!
My data source was from CloudWatch log, and I used log insight syntax to count the total number of occurrences of the “statusCode” field, and I thought it was int type.

Could you try the case that the data source is from CW log?
Thank you so much!!!

@grant2
Hope you can assist me with this feature which queries from the result of CW insight.

Thank you sooooooo much!!!

1 Like

I do not have Cloudwatch as a datasource.