"count()" of 720, but when selecting "last()" the result is "no data"

[blg]

I’m trying to create an alert rule to get notified when a certain backend no longer pushes a value called ‘export_interval’ to the Influx database.

The problem I’m facing is that the following query results in no data:

SELECT last("export_interval") FROM "ABC" WHERE $timeFilter GROUP BY "backend_name", "environment"

If I change last to count the result is 720.

SELECT count("export_interval") FROM "ABC" WHERE $timeFilter GROUP BY "backend_name", "environment"

How can there be no last, if there is a count?

I’ve tried all combinations of “Format as” and the three buttons on the right:

[yosiasz]

what happens if you try

SELECT last("export_interval") FROM "ABC" WHERE $timeFilter

Does one really need group by when it is last?

[blg]

Still “no data” when I remove the "group-by"s. However, I do need them, since I want to see three separate last values, each from a different backend.

[yosiasz]

what data source is this? influxdb?

[blg]

Yes, the data source is influxdb.

[grant2]

Can you share the screenshots of your entire alert rule configuration, along with the preview of the output (click the blue Preview alerts button). For example:

A: the non-working LAST query (and separately, the working COUNT query)
B: the reduction or classic condition expression
C: the expression that you are alerting on

[blg]

A1:
Non working LAST:

A2: working COUNT

B: I don’t have that yet, as there is no data to reduce.
C: I don’t have that yet, as there is no data to alert on.

[blg]

Do you think this is a bug, or do you need more information?