What are the requirements in order for the event log to collect backlog metrics?

[190809]

I am trying to use the event log to collect metrics on the 'flow_progess' under the 'event_type' field. In the the docs it suggests that this information may not be collected based on the data source and runtime used (see screenshot). Can anyone let me know what these requirements are for backlog metrics to be collected please?

[User16539034020]

Thanks for contacting Databricks Support! 

I understand that you're looking for information on unsupported data source types and runtimes for the backlog metrics. Unfortunately, we currently have not documented that information. It's possible that some types may not be supported, but we haven't determined the specific version or runtime yet.

If you could provide the detail error message encountered during the query, we would be able to assist with debugging. Thank you!

Databricks Support