Warehouse : Long-Running Query Detected – Impacting Fabric Capacity

[PrachiJain_2025]

Warehouse : Long-Running Query Detected – Impacting Fabric Capacity

Hello Everyone,

We’ve identified a system query that appears to have been running continuously since 2025-02-16, and it's still active. Throttling issues we've been facing on our Fabric capacity.

The query that is up and running is : 

(@source nvarchar(256))SELECT type, data FROM sys.fn_MSxe_read_event_stream (@source, 0)

1. What is the purpose of this query, and under what conditions does it typically run?
2. Could this long-running process be impacting capacity performance or causing throttling?
3. Is it safe to terminate this session manually, or is it tied to an essential system process?

Please advise on it.

How can we trace Operation :  Warehouse Query , Run by User : System that is cosuming more CU (See attached screenshot)

Thank you

Prachi Jain

[V-yubandi-msft]

Hi @PrachiJain_2025 ,

Has your issue been resolved, or do you require any further information? Your feedback is valuable to us. If the solution was effective, please mark it as 'Accepted Solution' to assist other community members experiencing the same issue.

[V-yubandi-msft]

Hi @PrachiJain_2025 ,

We haven’t received a response yet and want to ensure the solution met your needs. If you need any further assistance, feel free to reach out we’d be happy to help. If everything is working as expected, kindly mark it as Accepted as solution.

Thank You.

[V-yubandi-msft]

Hi @PrachiJain_2025 ,

May I ask if you have resolved this issue? If so, please mark the helpful reply and accept it as the solution. This will be helpful for other community members who have similar problems to solve it faster.

 

Thank you.

[V-yubandi-msft · Accepted solution]

Hi @PrachiJain_2025 ,

Thank you for engaging with the Microsoft Fabric Community.

1. The query sys.fn_MSxe_read_event_stream(@source) is a system level function utilized internally by SQL Server and Fabric for monitoring, diagnostics, and event tracing. It is not intended for regular users to execute directly and typically operates under system or telemetry processes.

FYI:

sys.fn_MSxe_read_event_stream (Transact-SQL) - SQL Server | Microsoft Learn

2. If a query continues running or becomes stuck, it can consume significant resources such as Compute Units , memory, and input/output operations. This can result in capacity throttling and slow down other tasks. Given that this query has been running since 16th Feb 2025, it is likely contributing to the performance issues.

3. If the session appears idle or stuck (no active processing or resource usage), it is safe to terminate it. However, as this is related to system diagnostics, proceed with caution. Can you check Monitor the session's CPU, memory, and IO usage briefly, and if there's no activity, terminate it to free up resources.

If my response resolved your query, kindly mark it as the Accepted Solution to assist others. Additionally, I would be grateful for a 'Kudos' if you found my response helpful.