Mirroring SQL Endpoint Capacity Usage

Hi All,

I've been working extensively with the Open Mirroring Database item in Microsoft Fabric, but I'm still trying to fully understand how its capacity (CU) consumption is calculated.

From my understanding, the internal operations include components such as:

• OneLake Write via Redirect
• OneLake Iterative Read via Proxy
• OneLake Read via Redirect
• OneLake Read via Proxy
• OneLake Write via Proxy
• OneLake Other Operations

My assumption is that these workloads account for activities such as data ingestion, CSV-to-Parquet conversion, data maintenance, vacuum operations, and other background processing required to keep the mirrored database operational.

What I do not understand is the Warehouse SQL Endpoint Query Usage metric.

On 11 August, this metric increased dramatically in our environment and has remained significantly elevated ever since. For one particular Open Mirroring Database item, usage increased from approximately 7K CU to 34K CU, and I am trying to determine what contributes to this workload and why it changed so suddenly.

Before: Screenshot

After: Screenshot

Another observation is related to the Run By filter in the Capacity Metrics App.

Prior to 10 August, I was able to filter consumption by individual user identities and clearly distinguish activity generated by specific users from activity generated by the system.

However, from around 10/11 August, all user-generated activity appears to be grouped under a generic "User" identity, and individual users can no longer be distinguished or filtered.

Before 10 August: Screenshot showing identifiable users

After 10 August: Screenshot showing only "User"

I don't understand what this new User identity represents. Is it an aggregation of all user-generated activity, a new classification introduced by the metering changes, or something else entirely?

My current theory is that both the increase in Warehouse SQL Endpoint Query Usage and the change in the Run By filter may be related to the recent Fabric capacity metering changes, but I have not been able to find any documentation that clearly explains this behavior.

Can anyone provide insight into the following?

1. What specifically contributes to Warehouse SQL Endpoint Query Usage for an Open Mirroring Database?
2. Do any of the internal mirroring processes execute through the SQL Endpoint and therefore appear under this metric?
3. Did the recent Fabric metering changes alter how these operations are classified or billed?
4. What exactly does the "User" identity represent in the Run By filter?
5. Why did individual user identities disappear after 10 August and become a generic "User" value?
6. Is the new User Identity dimension connected to the recent metering changes?
7. Has the attribution model for user-generated workloads changed, resulting in individual users being grouped into a single category?

Any clarification would be greatly appreciated, as these changes make it difficult to understand capacity consumption patterns and compare usage before and after 10 August.

Thanks!