Wait Type PREEMPTIVE_COM_GETDATA

Wait statistics, in the context of SQL Server, refer to the amount of time that a query spends waiting to access data in the database. When a client application requests data from the database, the request is placed in a queue and the client application must wait for its turn to access the data. The time that the query spends waiting is called a "wait" and is tracked by SQL Server. This information can be used to identify potential performance bottlenecks and optimize the performance of the database. Wait statistics are commonly used by database administrators to diagnose and troubleshoot performance issues in SQL Server.

SQL Server uses wait types to provide insights into where tasks might experience delays. The PREEMPTIVE_COM_GETDATA wait type is specific to SQL Server’s interaction with external components, particularly when calling COM (Component Object Model) objects. This wait type occurs when SQL Server is executing a COM-based request and is waiting for the external process to return data. Let’s dive into what this means, when it happens, and how to address it.

What Is the PREEMPTIVE_COM_GETDATA Wait Type?

The PREEMPTIVE_COM_GETDATA wait type appears when SQL Server needs to call an external COM object to retrieve data. Since these calls are made outside SQL Server’s process, they are handled in preemptive mode, meaning SQL Server yields the CPU to allow the external operation to complete.

While this is a normal behavior when working with external components, prolonged waits can impact SQL Server’s performance and the responsiveness of dependent processes.

When Does PREEMPTIVE_COM_GETDATA Appear?

This wait type typically occurs in scenarios such as:

• Integration with External Systems – When SQL Server interacts with external COM-based applications or services.
• OLE Automation Procedures – If SQL Server is using OLE automation stored procedures like sp_OAGetProperty to retrieve data.
• Linked Server Queries – When querying data from a linked server that uses a COM-based provider.
• Extended Stored Procedures – When using extended stored procedures that rely on COM components.

Why PREEMPTIVE_COM_GETDATA Waits Matter

Some PREEMPTIVE_COM_GETDATA waits are expected in environments that rely on external COM components. However, excessive or prolonged waits can indicate inefficiencies or bottlenecks. Common causes include:

• Slow External Systems – The COM component or external system may be slow to respond, causing SQL Server to wait.
• Network Latency – If the external component is accessed over a network, high latency can increase wait times.
• Resource Constraints – Limited CPU, memory, or disk resources on the external system can delay data retrieval.
• Frequent COM Calls – Over-reliance on COM-based processes can result in high cumulative wait times.

How to Address PREEMPTIVE_COM_GETDATA Waits

If PREEMPTIVE_COM_GETDATA waits are causing performance issues, consider these strategies:

• Optimize COM Interactions – Reduce the frequency of COM calls or batch them together where possible to minimize overhead.
• Improve External System Performance – Ensure the external system or COM component has sufficient resources (CPU, memory, disk) to handle requests efficiently.
• Check Network Performance – Optimize network connectivity between SQL Server and the external system to reduce latency.
• Avoid Excessive OLE Automation – Consider alternative methods for data retrieval that do not rely on COM-based operations.
• Monitor Linked Servers – If using linked servers, ensure their configurations are optimized and the data provider is performing well.

Monitoring PREEMPTIVE_COM_GETDATA Waits

To track this wait type, use SQL Server’s sys.dm_os_wait_stats to analyze wait statistics over time. You can also monitor specific queries or processes causing these waits using dynamic management views like sys.dm_exec_requests. Tools like Database Health Monitor provide real-time visibility into wait types, making it easier to diagnose and resolve issues efficiently.

Stedman Solutions specializes in SQL Server performance tuning, offering expert services to optimize your database environment and address wait types like PREEMPTIVE_COM_GETDATA. Our Database Health Monitor tool gives you powerful insights into system performance, helping you keep your SQL Server running smoothly. For managed services and tailored support, visit Stedman Solutions and let us help you achieve optimal SQL Server performance.

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Applies to

• SQL Server 2016
• SQL Server 2017
• SQL Server 2019
• SQL Server 2022

Related Waits

See Also

• More About PREEMPTIVE_COM_GETDATA