SQL Server Extended Events: A Comprehensive Guide for Dev

Hello Dev, if you’re a database administrator or developer who works with SQL Server, then you’re probably familiar with SQL Server Profiler. However, did you know that SQL Server Profiler has been deprecated since SQL Server 2012? That’s where SQL Server Extended Events (XEvents) comes in. XEvents is a lightweight eventing infrastructure that allows you to collect and analyze diagnostic information to troubleshoot issues and monitor SQL Server performance. In this article, we’ll dive deep into the world of SQL Server Extended Events, discussing everything from the basics to advanced topics.

Table of Contents

Heading
Description
1. What Are SQL Server Extended Events?
An introduction to what SQL Server Extended Events are and why they are important.
2. The XEvents Architecture
A detailed look at the XEvents architecture and how it works.
3. Creating an XEvents Session
A step-by-step guide on how to create an XEvents session.
4. XEvents Targets and Actions
An overview of XEvents targets and actions.
5. XEvents Events and Predicates
A look at XEvents events and predicates.
6. Filtering XEvents Data
How to filter and refine XEvents data.
7. Working with XEvents XML Data
A guide on how to work with XEvents XML data.
8. Advanced XEvents Concepts
An in-depth look at advanced XEvents concepts like using custom events and working with the ring buffer target.
9. Automating XEvents with PowerShell
A tutorial on how to automate XEvents with PowerShell.
10. Monitoring SQL Server with XEvents
How to use XEvents to monitor SQL Server performance and troubleshoot issues.
11. XEvents Best Practices
A collection of best practices and tips for using XEvents.
12. XEvents FAQs
A list of frequently asked questions about SQL Server Extended Events.

1. What Are SQL Server Extended Events?

SQL Server Extended Events (XEvents) is a lightweight eventing infrastructure that has been available in SQL Server since SQL Server 2008. XEvents provides users with a powerful way to collect diagnostic information to troubleshoot issues and monitor SQL Server performance.

XEvents is designed to be more lightweight and efficient than its predecessor, SQL Server Profiler. While SQL Server Profiler uses a more complicated, resource-intensive architecture to capture data, XEvents uses a simpler architecture that doesn’t require as many resources. This makes it a great choice for users who need to gather data without impacting SQL Server performance.

Overall, XEvents is a key tool for database administrators and developers who need to understand what’s happening in their SQL Server environment.

Advantages of XEvents

There are several advantages to using XEvents over SQL Server Profiler:

  • XEvents is more lightweight and efficient than SQL Server Profiler, so it doesn’t impact server performance as much.
  • XEvents offers a more flexible and powerful filtering system than SQL Server Profiler.
  • XEvents allows users to collect more detailed information than SQL Server Profiler, including information about waits and latches.
  • XEvents offers a more modern and extensible platform for collecting diagnostic information.

Disadvantages of XEvents

However, there are a few disadvantages to using XEvents:

  • XEvents has a steeper learning curve than SQL Server Profiler.
  • Many users are still more comfortable using SQL Server Profiler.
  • XEvents does not support all of the same events as SQL Server Profiler.

When to Use SQL Server Extended Events

XEvents is ideal for users who need to capture diagnostic information with minimal impact on server performance. It’s a great tool for troubleshooting specific issues, monitoring performance, and understanding what’s happening behind the scenes in your SQL Server environment.

However, it’s important to note that XEvents is not always the best tool for the job. In some cases, SQL Server Profiler or other tools may be better suited to your needs. It’s important to understand the strengths and weaknesses of each tool so that you can choose the right one for the job.

2. The XEvents Architecture

Before we dive into how to use XEvents, it’s important to understand the basics of how XEvents works.

The XEvents Design Goals

The XEvents architecture is designed to meet several key design goals:

  • Lightweight and efficient: XEvents is designed to have minimal impact on server performance.
  • Flexible and extensible: XEvents is designed to be easy to extend and customize.
  • Reliable and scalable: XEvents is designed to be a reliable and scalable platform for collecting diagnostic information.

The XEvents Architecture Overview

The XEvents architecture consists of several key components:

  • Events: Events are predefined points in SQL Server code where diagnostic information can be collected.
  • Actions: Actions are prebuilt routines that can be executed when an event occurs.
  • Targets: Targets are destinations that receive the data collected by events and actions.
  • Sessions: Sessions are collections of events, actions, and targets that are configured to capture diagnostic information.
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When an event occurs, the actions associated with that event are executed. These actions can manipulate the data collected by the event, or they can send the data to a target for further processing. Targets can be anything from a file on disk to a remote system. Sessions are configured to capture specific events and send the data to specific targets.

The XEvents Ring Buffer Target

The XEvents ring buffer target is a special target that is used to store event data in memory. This target is particularly useful for monitoring SQL Server performance because it allows you to capture data without having to write it to disk. The ring buffer target is also useful for debugging because it allows you to view data that was collected before a problem occurred.

3. Creating an XEvents Session

To use XEvents, you first need to create an XEvents session. An XEvents session is a configuration object that defines the events, actions, and targets that will be used to capture diagnostic information.

Creating an XEvents Session Using SSMS

The easiest way to create an XEvents session is to use SQL Server Management Studio (SSMS). Here’s how:

  1. Open SSMS and connect to the SQL Server instance you want to monitor.
  2. Select the “Management” node in the Object Explorer.
  3. Right-click on “Extended Events” and choose “New Session…”.
  4. Enter a name for the session and choose the events you want to capture.
  5. Choose the actions and targets you want to use.
  6. Click “OK” to save the session.

Creating an XEvents Session Using T-SQL

You can also create an XEvents session using T-SQL. Here’s an example:

CREATE EVENT SESSION [MySession] ON SERVERADD EVENT sqlserver.sql_statement_completed(ACTION(sqlserver.session_id, sqlserver.client_hostname, sqlserver.client_app_name,sqlserver.plan_handle, sqlserver.query_hash))ADD TARGET package0.ring_buffer;GO

This will create an XEvents session called “MySession” that captures the “sql_statement_completed” event and stores the data in the ring buffer target.

Starting and Stopping an XEvents Session

Once you’ve created an XEvents session, you can start and stop it using SSMS or T-SQL. Here’s an example using T-SQL:

ALTER EVENT SESSION [MySession] ON SERVER STATE = START;GOALTER EVENT SESSION [MySession] ON SERVER STATE = STOP;GO

4. XEvents Targets and Actions

Targets and actions are an important part of the XEvents architecture. Targets are destinations that receive the data collected by events and actions. Actions are prebuilt routines that can be executed when an event occurs.

XEvents Targets

XEvents supports several different types of targets:

  • File: Writes event data to a file on disk.
  • Event File: Writes event data to an event file on disk.
  • Ring Buffer: Stores event data in memory.
  • Event Counter: Used to capture performance counter data.
  • Event Pairing: Used to create pairs of related events.
  • Custom: Allows users to create their own targets.

XEvents Actions

XEvents supports several different types of actions:

  • Action: Executes a Transact-SQL statement.
  • Send: Sends data to a target.
  • Event Counter: Increments a performance counter.
  • Event Pairing: Matches related events.
  • Event Session: Changes the current session.
  • Stack Trace: Captures a stack trace.
  • Dispatch SQL: Sends a SQL statement to an event dispatcher.
  • Custom: Allows users to create their own actions.

5. XEvents Events and Predicates

Events and predicates are the heart of XEvents. Events are predefined points in SQL Server code where diagnostic information can be collected. Predicates are filters that allow you to capture only the data you’re interested in.

XEvents Events

XEvents supports hundreds of different events that you can use to capture diagnostic information. Here are some of the most commonly used events:

  • sqlserver.error_reported: Captures errors that occur in SQL Server.
  • sqlserver.module_end: Captures when a module (like a stored procedure or trigger) finishes executing.
  • sqlserver.rpc_completed: Captures when a remote procedure call (RPC) completes.
  • sqlserver.sql_batch_completed: Captures when a SQL batch completes.
  • sqlserver.sql_statement_completed: Captures when a SQL statement completes.
  • sqlserver.transaction_beginning: Captures when a transaction begins.
  • sqlserver.transaction_committing: Captures when a transaction is being committed.
  • sqlserver.transaction_rollback: Captures when a transaction is rolled back.

XEvents Predicates

XEvents supports several different types of predicates:

  • Comparison: Compares the value of an event field to a constant.
  • Like: Matches the value of an event field to a pattern.
  • Exists: Checks if an event field exists.
  • Scalar: Computes a scalar value.
  • Logical: Combines multiple predicates with logical operators.

6. Filtering XEvents Data

XEvents offers a flexible and powerful filtering system that allows you to capture only the data you’re interested in. Here are some ways you can filter XEvents data:

Filtering by Event Fields

You can filter XEvents data by the value of an event field. Here’s an example that captures only events where the statement text contains the word “SELECT”:

CREATE EVENT SESSION [MySession] ON SERVERADD EVENT sqlserver.sql_statement_completed(ACTION(sqlserver.session_id, sqlserver.client_hostname, sqlserver.client_app_name,sqlserver.plan_handle, sqlserver.query_hash)WHERE sqlserver.sql_text LIKE '%SELECT%')ADD TARGET package0.ring_buffer;GO

Filtering by Predicate

You can also filter XEvents data using a predicate. Here’s an example that captures only events where the duration of the statement is greater than 5000 microseconds:

CREATE EVENT SESSION [MySession] ON SERVERADD EVENT sqlserver.sql_statement_completed(ACTION(sqlserver.session_id, sqlserver.client_hostname, sqlserver.client_app_name,sqlserver.plan_handle, sqlserver.query_hash)WHERE sqlserver.duration > 5000)ADD TARGET package0.ring_buffer;GO

Filtering by Multiple Events

You can also filter XEvents data by capturing multiple events and filtering based on the values of multiple event fields. Here’s an example that captures both the “sql_statement_completed” and “transaction_rollback” events and filters based on the value of the “error_number” field:

CREATE EVENT SESSION [MySession] ON SERVERADD EVENT sqlserver.sql_statement_completed(ACTION(sqlserver.session_id, sqlserver.client_hostname, sqlserver.client_app_name,sqlserver.plan_handle, sqlserver.query_hash, sqlserver.error_number)),ADD EVENT sqlserver.transaction_rollback(ACTION(sqlserver.session_id, sqlserver.client_hostname, sqlserver.client_app_name,sqlserver.transaction_id, sqlserver.error_number))WHERE sqlserver.error_number > 0ADD TARGET package0.ring_buffer;GO

7. Working with XEvents XML Data

XEvents data is stored in XML format. This allows for easy parsing and processing of the data. Here are some tips for working with XEvents XML data:

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Extracting XEvents Data Using T-SQL

You can extract XEvents data using T-SQL. Here’s an example:

SELECTCONVERT(XML, event_data).value('(/event/@name)[1]', 'varchar(50)') AS EventName,CONVERT(XML, event_data).value('(/event/@timestamp)[1]', 'datetime2(7)') AS EventTime,CONVERT(XML, event_data).value('(/event/action[@name="session_id"]/value)[1]', 'int') AS SessionID,CONVERT(XML, event_data).value('(/event/data[@name="duration"]/value)[1]', 'bigint') AS DurationFROM sys.fn_xe_file_target_read_file('C:\Temp\MySession*.xel', null, null, null) x;

This will extract XEvents data from all files in the “C:\Temp” directory that match the pattern “MySession*.xel”.

Viewing XEvents Data Using SSMS

You can also view XEvents data using SQL Server Management Studio (SSMS). Here’s how:

  1. Connect to the SQL Server instance that captured the XEvents data.
  2. Expand the “Management” node in the Object Explorer.
  3. Expand the “Extended Events” node and select the event session you want to view.
  4. Right-click on the event session and choose “Watch Live Data”.
  5. A live data window will appear showing the XEvents data.

8. Advanced XEvents Concepts

Now that we’ve covered the basics of XEvents, let’s dive into some more advanced topics.

Creating Custom Events

XEvents allows you to create your own custom events. This can be useful if you want to capture data that’s not available in the standard set of events. Here’s how:

  1. Create
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