Wait Type PREEMPTIVE_OS_REPORTEVENT

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.

The SQL Server PREEMPTIVE_OS_REPORTEVENT wait type is a type of wait that occurs when a session is waiting for the operating system to report an event. This type of wait is typically associated with asynchronous I/O operations in SQL Server, such as reading or writing to a file, or waiting for a response from the network.

When a session is waiting on the PREEMPTIVE_OS_REPORTEVENT wait type, it means that it is unable to proceed with its current operation until the operating system has reported the completion of the asynchronous I/O operation. This can cause delays and slow down the overall performance of the SQL Server instance.

To troubleshoot and resolve issues related to the PREEMPTIVE_OS_REPORTEVENT wait type, it is important to first determine what operation is causing the wait and then investigate why that operation is taking a long time to complete. This may involve looking at the queries or processes that are executing the asynchronous I/O operation, as well as any other operations that are running concurrently on the SQL Server instance.

In some cases, it may be necessary to optimize the queries or processes that are causing the PREEMPTIVE_OS_REPORTEVENT waits, or to adjust the workload on the SQL Server instance to reduce the occurrence of this wait type. It may also be necessary to adjust the settings of the asynchronous I/O operation to improve its performance and reduce the need for the operating system to report events.

Overall, the PREEMPTIVE_OS_REPORTEVENT wait type can be a useful indicator of potential performance issues related to asynchronous I/O in SQL Server, and can help DBAs and developers identify and resolve those issues to improve the performance of their databases.

Applies to

• SQL Server 2012
• SQL Server 2014
• SQL Server 2016
• SQL Server 2017
• SQL Server 2019
• SQL Server 2022

Related Waits

See Also

• More About PREEMPTIVE_OS_REPORTEVENT