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Applies to: 
SQL Server 2025 (17.x) Preview
SQL Server 2025 (17.x) Preview introduces the PREVIEW_FEATURES database scoped configuration option. This option enables features that are available for preview.
The following table identifies features originally released as preview their current status:
| Feature | Current status | Version of latest update | Description |
|---|---|---|---|
| AI_GENERATE_CHUNKS | Preview | RC 0 | Generate chunks of text from a given input text using an AI model. |
| Change event streaming | Preview | RC 0 | Stream changes from SQL Server to Azure Event Hubs. |
| CREATE VECTOR INDEX | Preview | RC 0 | Create an approximate index on a vector column to improve performances of nearest neighbors search. |
| VECTOR_SEARCH | Preview | RC 0 | Search for vectors similar to a given query vector using an approximate nearest neighbors vector search algorithm. |
| CREATE EXTERNAL MODEL | Preview | RC 0 | Supports local ONNX models hosted directly on the SQL Server file system. |
Caution
Preview features aren't recommended for production environments.
Preview features that become generally available in a subsequent cumulative update no longer require the database-scoped configuration option.
What is PREVIEW_FEATURES?
PREVIEW_FEATURES is a database-scoped configuration that lets you try out new SQL Server features before they're generally available. This option is intended for development and testing environments and shouldn't be used in production.
How do I enable the PREVIEW_FEATURES option ?
PREVIEW_FEATURES is a DATABASE SCOPED CONFIGURATION option, therefore you can enable it by executing the following code:
ALTER DATABASE SCOPED CONFIGURATION
SET PREVIEW_FEATURES = ON;
GO
SELECT * FROM sys.database_scoped_configurations
WHERE [name] = 'PREVIEW_FEATURES'
GO
Read more details in the DATABASE SCOPED CONFIGURATION page.
Do I need to enable PREVIEW_FEATURES to use AI functionalities in SQL Server 2025?
No, most AI features in SQL Server 2025 are already generally available (GA), including AI_GENERATE_EMBEDDINGS, CREATE EXTERNAL MODEL, and the vector data type and related functions. Only the features explicitly listed in the release notes document require the PREVIEW_FEATURES option to be enabled.
Does enabling PREVIEW_FEATURES make database a non-GA version?
No, enabling the PREVIEW_FEATURES configuration doesn't change the GA status of a database. The database remains GA even when preview features are enabled. This opt-in mechanism is designed to allow customers to test new features before they reach GA, without affecting the overall GA status of the database itself. However, it's important to note that after enabling preview features, if preview features are used and they involve persisted objects (like indexes), disabling PREVIEW_FEATURES later might cause errors unless those objects are removed or rebuilt.
Preview features should generally be used in development or testing environments, not in production, due to their experimental nature and potential for change.
How does a preview feature move to general availability (GA)?
Features are promoted to GA via a cumulative update (CU).
Can a CU update a preview feature without moving it to GA?
Yes. Preview features can be updated in CUs while remaining under the PREVIEW_FEATURES umbrella.
What happens when a feature under PREVIEW_FEATURES goes GA?
The feature becomes available regardless of the PREVIEW_FEATURES setting.
Can I enable and then disable the PREVIEW_FEATURES option at any time?
If no preview features were used, you can safely turn it off at any time. If preview features were used you can turn it OFF, but objects using those features will error out. Once the PREVIEW_FEATURES option is turned off, the database engine is unaware of those features so using them might return errors because the new commands aren't recognized at all.
Does using PREVIEW_FEATURES affect my backup and restore strategy?
No, the preview features setting doesn't affect database backup or restore. Databases remain compatible across cumulative updates and general releases. However, if you apply a cumulative update (CU) that improves a feature in preview and then restore that database to a previous version, the feature might not work as expected or might even error out. This is because the restored version might not recognize the updated syntax or behavior introduced in the newer CU. Therefore, while backup and restore operations themselves are unaffected, feature compatibility depends on the CU level of the target environment.
If at any point a preview feature requires changes that would make it incompatible with previous versions, we will clearly document those changes. In such cases, applying the update will require a manual step to ensure you're aware of the potential impact. Importantly, updates won't automatically make the database incompatible with previous versions. Even in these cases, we'll provide the ability to roll back to the previous CU if needed.
What if I'm not interested in using any preview features?
You can leave PREVIEW_FEATURES set to OFF. You retain full rollback and restore capabilities across CUs and GA. Any update to the features using the PREVIEW_FEATURES opt-in mechanism doesn't affect your database.
Can I enable only specific preview features?
The database scoped setting enables the usage of all preview features.
Is support available for preview features?
Yes, support is provided for preview features, similar to What's new in Azure SQL Database?
How do GDR patches affect PREVIEW_FEATURES?
GDR patches are orthogonal to CUs and don't affect the status of PREVIEW_FEATURES. Features moved to GA via CU require that CU to be applied; GDRs don't include feature payloads.