Understanding and Implementing SQL Server Extended Events for Custom Monitoring
When it comes to monitoring and troubleshooting in SQL Server, Extended Events (XE) is a powerful system that helps database administrators gain insight into the inner workings of their databases. SQL Server Extended Events is a lightweight performance monitoring system that enables users to collect data needed for diagnosing performance issues. In this comprehensive guide, we will delve into the world of Extended Events, discussing how you can leverage this feature for custom monitoring purposes.
What are SQL Server Extended Events?
SQL Server Extended Events is a general event-handling system for server systems. Designed to replace SQL Trace, which has been deprecated, XE offers a way to gather data about SQL Server, which can be used for diagnosis or monitoring. The system uses very few system resources, making it more efficient than the older SQL Profiler. Information about server behavior can be obtained without significant performance overhead, which is a key feature of Extended Events.
Extended Events utilizes a series of components: events, event fields, targets, actions, predicates, and sessions, among others, to help capture and analyze data. By creating sessions, users can track, collect, and process events while the Server is running, leading to a dynamic and continuous monitoring process.
Core Components of SQL Server Extended Events
Understanding the core components of Extended Events is crucial for configuring and utilizing the system effectively:
- Events: The point of execution within SQL Server when something occurs.
- Event Fields: Data from events providing extra detail.
- Targets: The destinations for event data, such as event files or ring buffers.
- Actions: Additional processes executed when an event occurs.
- Predicates: Filters to control which events to capture based on specific conditions.
- Sessions: Containers connecting events, targets, and predicates to capture event data.
When setting up a monitoring system with Extended Events, you define which events you’re interested in, the conditions under which you’re interested in those events, and what you want to do with the event data once it’s been captured.
Setting Up SQL Server Extended Events Session
To use Extended Events for custom monitoring, you need to first set up an XE session. Here are the step-by-step instructions for setting up a basic Extended Events session:
Step 1: Create a New Session
Create Event Session [YourSessionName] ON SERVER
This Transact-SQL command initializes a new Extended Events session. Replace [YourSessionName] with a name for your session.
Step 2: Add Events to the Session
Add Event sqlserver.error_reported
The ADD EVENT clause specifies which events the session should capture. In this example, the sqlserver.error_reported event is being added, which captures SQL Server error reports.
Step 3: Set Event Fields and Filters
Add Event sqlserver.error_reported
(Action(sqlserver.client_app_name, sqlserver.client_hostname, sqlserver.database_name)
Where ([severity]>10))
This expands upon Step 2, including ACTION to specify additional data (such as application name, hostname, and database name) and a predicate to filter events with a severity greater than 10.
Step 4: Define the Target for Event Data
Add Target package0.event_file(Set filename=N'path_to_file.xel', max_file_size=(5), max_rollover_files=(2))
An event file target is specified with a path, max size, and rollover file count.
Step 5: Set Session Options and Start the Session
With
(Startup_state = On,
Track_causality = On)
Alter Event Session [YourSessionName] ON SERVER
State = Start;
Finally, specify session options such as Startup_state (whether the session starts automatically when the Server is started) and Track_causality (which allows for tracking the order of events across related events). Once the session is created, you’ll start it with ALTER EVENT SESSION, replacing [YourSessionName] with the name of your session.
Monitoring SQL Server with Extended Events
After setting up the Extended Events session, monitoring SQL Server involves the following steps:
Analyze Data from a Session’s Target
Using XE’s GUI in SQL Server Management Studio (SSMS) or Transact-SQL scripts, analyze the data collected in your configured targets (typically, file targets are used for later analysis, while ring buffer targets are for real-time monitoring).
Modifying and Managing Extended Events Sessions
You can modify the definitions of active sessions as needed by using the ALTER EVENT SESSION command to change events, actions, and predicates without stopping the session. You can also use SSMS to graphically manipulate sessions.
Whether you are diagnosing server issues, assessing performance impact of the newly deployed features, or gathering data for later analysis, SQL Server Extended Events provides the flexibility, minimal performance impact, and depth of insights required for custom monitoring solutions.
Conclusion
In conclusion, SQL Server Extended Events is an invaluable tool for anyone charged with the task of monitoring and diagnosing issues within SQL Server environments. The capacity to customize which events to capture, combined with the detailed filtering options and various data handling targets, makes XE sessions an essential tool in the modern database administrator’s toolkit. While the setup might seem complex at first, the potential for tailored insights and detailed server behavior monitoring makes the learning curve a worthwhile investment.
Please note: While this guide aims to provide thorough instructions on setting up and utilizing Extended Events for custom monitoring in SQL Server, it is highly recommended to test configurations in a non-production environment first, to avoid unintended effects on your Server’s performance.
