Using `eval` to match all values (or existence) of a field

[flow2k]

Often, we can use eval(myField=someValue)) with aggregate functions like count and avg, as well as time function like per_day, to process matching events. Is there a way for eval to match all values (or equivalently, the existence) of a field? This would be useful for searches like:
timechart per_second(eval(status>-9999))

I tried timechart per_second(eval(status=*)) to no avail.

[elliotproebstel]

You can use eval(isnotnull(status)) to test for the existence of a field.

[tiagofbmm]

Hi

I believe the following is what you are looking for.

index=_internal
| timechart count(eval(source like "%")) as src

Let me know please

[flow2k]

Thanks for the answer, but I believe the issue with using count instead of per_second (as in my original post) is that it depends on the span - I will get different answers if span=1h vs span=1min. Would you agree?

[tiagofbmm]

Sorry I tested count and only now tested per_second. The results are coherent though, any aggregation function works the same here.

Answering to your question, yes surely you'll get different results depending on your timespan, because granularity is changing. It is acceptable and somehow expected to produce different results

[flow2k]

Okay, I tried this and it works too. Why does this work - is there documentation on this syntax? Thanks!

[tiagofbmm]

This works because the eval functions the same way as the syntax of the where command. The "%" replaces the "*".

Feel free to accept the answer if you think it clarified your question