How to Enable Query Store in SQL Server: A Step-by-Step Guide

In my previous post about Query Store, I wrote about the four key benefits to enabling Query Store. Now that I’ve convinced you to turn it on, how do you do that?

One thing to point out is that in SQL Server 2022 and above, when creating a new database from the SSMS GUI or by simply using the CREATE DATABASE MyNewDB syntax, the Query Store option will be on by default. For databases restored to SQL Server 2016 or later, the Query Store’s status from the original system will remain unchanged when the database is restored on the new instance.

Let’s go through the three ways to enable Query Store.

1. Manually in SQL Server Management Studio
2. Using T-SQL
3. Using PowerShell

1. Enabling Query Store using SQL Server Management Studio:

Since you’re likely already comfortable using SQL Server Management Studio for queries and database maintenance, SMSS does offer a convenient, familiar method for getting started with Query Store.

Steps to Enable Query Store using SSMS

1. Connect to a SQL Server instance running SQL Server 2016 or higher.
2. Click the ‘+’ sign next to the Databases folder to expand and see the list of databases.
3. Right-click on the database name and select “Properties.”
4. Left-click the “Query Store” option on the left-hand side of the GUI.
5. Change the Operation Mode(Requested) option from “Off” to “Read write.”
6. Click OK to apply the change and enable Query Store.

Further Details

Here is what you will see after step 3. The Query Store option mentioned in step 4 is at the bottom of the list of options, like the below.

Left-clicking that Query Store option will cause the below to show up on the right of the SSMS GUI.

What you see when you do that are the existing defaults on 2019 and above. If you are enabling Query Store on versions 2016 or 2017, you will want to adjust additional defaults. Prior to 2019, the default for “Query Store Capture Mode” was “All.” Change this option to “Auto” instead.

Furthermore, the default for Max_Storage_Size_MB was far too low in 2016 and 2017 and could be better in 2019 as well. This value represents the maximum amount of space that Query Store data will occupy in the database in which it was enabled. A good default value to start with is 2048 MB. It may be necessary to adjust that to 4096 MB at the high end in order to capture queries for the entire length of the “Stale Query Threshold (Days)” value.

The “Stale Query Threshold (Days)” option controls how many days of Query Store data will be kept. If the max storage size is set too low for a retention value of 30 days, then Query Store will start deleting collected data in the system tables to keep Query Store below the max storage size. This could result in having less data available than you intend for troubleshooting.

The rest of the defaults are acceptable and so could be left alone without concern.

2. Enabling Query Store using T-SQL

The T-SQL language is, of course, the language of SQL Server. It is often more flexible than the SSMS GUI. Notice in the screenshot up above that there is a “Script” button. If you click that instead of clicking “ok” in the UI, then SQL Server will script out the options in the GUI into a query window. This will allow you to see what the GUI does. Using T-SQL, it is easier to enable Query Store on multiple databases. You can use a construct like sp_msforeachdb to enable Query Store for multiple databases at once.

USE [master]
GO
ALTER DATABASE [MyDB] SET QUERY_STORE = ON
GO
ALTER DATABASE [MyDB] SET QUERY_STORE (OPERATION_MODE = READ_WRITE, MAX_STORAGE_SIZE_MB = 2048)
GO

3. Enabling Query Store using PowerShell

Many accidental DBAs, those folks who were “voluntold” to start managing SQL Server, are network engineers, sysadmins, or cloud admins. Automation is often music to their ears, and in the Windows universe, PowerShell is a go-to method for automating tasks. Consequently, using PowerShell to automate the enabling of Query Store may feel natural to accidental DBAs. For the below command, the DBATools module will be needed in your environment.

Below is how Query Store could be enabled on all user databases on an instance of SQL Server. If you only want to enable Query Store on a few select databases on an instance, then add the -Database parameter with a comma-separated list of databases.

Set-DbaDbQueryStoreOption -SqlInstance ServerA -State ReadWrite ​

-FlushInterval 900 -CollectionInterval 60 -MaxSize 4096 ​

-CaptureMode Auto -CleanupMode Auto -StaleQueryThreshold 30, -WaitStatsCaptureMode ON

Also, if your SQL Server environment has the Registered Server feature set up, then PowerShell can be used to read the servers registered there, loop over them, and enable Query Store on all user databases across your environment. This would be done using the Get-DbaRegServer command in the DBATools module.

Trace Flags for Query Store

If you aren’t familiar with Trace Flags, these are numbers that Microsoft uses to enable certain kinds of behavior in the database engine. They are occasionally meant to be short-term fixes, and later the functionality in a trace flag is built into how the SQL Server database engine works. This is the case for trace flags and Query Store. There are two trace flags to know about and enable. Notice that flag 7752 isn’t needed on SQL Server 2019 and above.

Trace Flag 7745—This prevents Query Store data from writing to disk prior to shutdown or failover process so it doesn’t delay a shutdown or failover.​

Trace Flag 7752 – Loads Query Store data to memory asynchronously from query execution. This default is built into the engine in SQL Server 2019.​

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