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Applies to: 
SQL Server 2025 (17.x) Preview
This article describes requirements, and limitations for SQL Server 2025 (17.x) Preview.
This article is updated for release candidate (RC) 0.
Preview features
Explore preview development features with a new PREVIEW_FEATURES database scoped configuration. Enable PREVIEW_FEATURES to test some features, such as vector indexes. This configuration lets you try select features in preview even after SQL Server reaches general availability. These features will become generally available in future cumulative updates. When a cumulative update provides general availability for a feature, the database-scoped configuration is no longer be necessary for that feature.
To use these features, enable the PREVIEW_FEATURES database scoped configuration.
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.
All other features described in the What's new in SQL Server 2025 Preview article are aligned with the release of SQL Server. They don't require enabling the preview feature database scoped configuration.
For more information, review Opt in for preview features - FAQ.
Optimized Halloween protection not available
The Optimized Halloween protection feature is not currently available in SQL Server 2025 (17.x) Preview RC 0.
Breaking changes
SQL Server 2025 (17.x) Preview introduces breaking changes to a few SQL Server Database Engine features. To learn more, review Breaking changes in SQL Server 2025 preview.
Build number
| Build | Version number | Date |
|---|---|---|
| Preview (RC 0) | 17.0.900.7 | August 20, 2025 |
| Preview (CTP 2.1) | 17.0.800.3 | June 16, 2025 |
| Preview (CTP 2.0) | 17.0.700.9 | May 19, 2025 |