Unexpected watermark delay when there is no processing in Azure Stream Analytics

Question

When we were doing monitoring on our Azure Stream Analytics resource, we notice that the watermark delay stay constant/ fluctuate at 1 second range at 2s, some other ASA instance at 6s, given there is no events to be processed at all. The only input is from Azure Event Hub and we have checked that there is no incoming messages at all during the period.

We expect watermark delay to show 0 when there's no events to be processed.

Could this be a bug or is there a rationale behind this?

Thank you.

Answer 1

Hello @Ivan Tioh ,
Thanks for the question and using MS Q&A platform.

As we understand the ask here is why the watermark delay monitor is showing values > 0 , when there are NO inputs for , please do let us know if its not accurate.

I am not sure if you are using the below clause in the query ( you can run the query with this also )

timestamp by eventTime

and it does goes back to 0 when there are NO events.

Please do let me if you have any queries.
Thanks
Himanshu

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