Wait Type SQLTRACE_INCREMENTAL_FLUSH_SLEEP

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 provides detailed insights into its processes through wait types, which indicate where tasks might be delayed. One such wait type, SQLTRACE_INCREMENTAL_FLUSH_SLEEP, is tied to SQL Trace, a legacy feature used to capture and record database activity. This wait type occurs when SQL Server is pausing to flush trace data incrementally to a file. In this post, we’ll explore what this wait type means, why it appears, and how you can address it in your SQL Server environment.

What Is the SQLTRACE_INCREMENTAL_FLUSH_SLEEP Wait Type?

The SQLTRACE_INCREMENTAL_FLUSH_SLEEP wait type occurs when SQL Server’s SQL Trace subsystem is sleeping before flushing trace data to a file. This is part of the process of incrementally saving trace data, which helps reduce resource usage by writing in intervals rather than continuously.

This wait type is typical in environments where SQL Trace is actively running, particularly in high-activity databases where a significant amount of trace data is being generated.

When Does SQLTRACE_INCREMENTAL_FLUSH_SLEEP Appear?

This wait type is most commonly seen in the following scenarios:

• Active SQL Trace Sessions – When trace sessions are capturing significant database activity.
• High Database Activity – In busy systems where large volumes of trace data are being generated and periodically flushed to disk.
• Legacy Workloads – Environments still relying on SQL Trace instead of more modern tools like Extended Events.

Why SQLTRACE_INCREMENTAL_FLUSH_SLEEP Waits Matter

While SQLTRACE_INCREMENTAL_FLUSH_SLEEP waits are expected in systems using SQL Trace, they can indicate potential performance issues if they occur frequently or for extended periods. Some common causes include:

• High Trace Data Volume – Excessive activity captured by trace sessions can lead to frequent flush operations.
• Slow Disk I/O – Writing trace data to slow or overburdened storage can extend flush times and increase wait occurrences.
• Outdated SQL Trace Usage – Continued reliance on SQL Trace instead of modern tools like Extended Events may lead to inefficiencies.

How to Address SQLTRACE_INCREMENTAL_FLUSH_SLEEP Waits

To reduce the impact of this wait type, consider these strategies:

• Optimize Trace Sessions – Minimize the number of events and columns being captured in trace sessions to reduce data volume.
• Switch to Extended Events – Use Extended Events, a more efficient and modern replacement for SQL Trace, for activity monitoring and diagnostics.
• Improve Disk Performance – Ensure trace files are written to fast, reliable storage to minimize delays in flushing data.
• Limit Trace Usage – Avoid running trace sessions continuously unless absolutely necessary. Use them selectively for diagnostics.
• Monitor Trace Impact – Regularly review the resource impact of trace sessions using tools like sys.traces to ensure they are not causing excessive overhead.

Monitoring SQLTRACE_INCREMENTAL_FLUSH_SLEEP Waits

To monitor this wait type, use SQL Server’s sys.dm_os_wait_stats to track occurrences and durations. Additionally, analyze active trace sessions using sys.traces to ensure they are optimized for minimal impact. For a comprehensive view of wait types and system performance, tools like Database Health Monitor provide powerful insights to help you identify and resolve potential bottlenecks.

Stedman Solutions specializes in SQL Server performance tuning, offering managed services to help you optimize your environment and minimize wait types like SQLTRACE_INCREMENTAL_FLUSH_SLEEP. Whether you need assistance transitioning to Extended Events or improving overall system efficiency, we can help. Our Database Health Monitor tool provides detailed wait type analysis and performance metrics, making it easier to keep your SQL Server environment running smoothly. Contact us today to learn more about our managed services and how we can support your SQL Server needs.

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Applies to

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• More About SQLTRACE_INCREMENTAL_FLUSH_SLEEP