Announcing SQL Server 2025 Release Candidate 0 (RC0)

We are excited to announce the availability of SQL Server 2025 Release Candidate 0 (RC0), building on the momentum of the first public preview released on May 15, 2025. This release marks a significant step forward in database innovation, introducing new development features and critical enhancements to performance, security, and analytics.

Focus on Preview Features: Opt-In Innovation

With RC0, SQL Server 2025 introduces a new way to experiment and adopt cutting-edge capabilities through the PREVIEW_FEATURES database scoped configuration. This opt-in mechanism empowers developers and database administrators to explore new features in a controlled, flexible manner. To learn more, please review the release notes for detailed guidance on activating and leveraging these preview features.

What’s New in RC0?

AI Enhancements

• Vector Search and Index:
• Easily create vector indexes and execute vector searches using the PREVIEW_FEATURES configuration.
• Better intra-query parallelism with hyperthreading.
• Enabled usage of vectors on MacOS via Rosetta 2 translation layer.
• Text Chunking: The AI_GENERATE_CHUNKS feature enables efficient text chunking, available via PREVIEW_FEATURES.
• ONNX Model Integration: CREATE EXTERNAL MODEL now supports local ONNX models hosted directly in SQL Server, enabled through PREVIEW_FEATURES.
• Improved Metadata: The sys.vector_indexes view now follow established naming convention and inherits columns from sys.indexes.

Linux Support

• Broaden Your Linux Choices with Ubuntu 24.04 Support

SQL Server 2025 RC0 now runs on Ubuntu 24.04 LTS, giving you more flexibility to standardize on the latest long‑term support Linux distribution.

• Starting in SQL Server 2025 (17.x) Preview, TLS 1.3 is enabled by default.

Database Engine Improvements

• Time-bound extended event sessions stop automatically after the specified time elapses.

• Cardinality Estimation (CE) Feedback for Expressions—cache persistence:

Learns from repeated query patterns to pick better row estimates and plans. With persistence, that learning will survive restarts and failovers for steadier performance and less retuning.

Analytics

• PolyBase now supports managed identity communications to Microsoft Azure Blob Storage and Microsoft Azure Data Lake Storage.

Language and Query Features

• JARO_WINKLER_DISTANCE returns float (previously real).
• JARO_WINKLER_SIMILARITY returns int (previously real).
• REGEXP_REPLACE and REGEXP_SUBSTR now support large object (LOB) types (varchar(max) and nvarchar(max)).
• REGEXP_LIKE is now SARGable, allowing index usage for faster query execution.

Availability and Security

• SQL Server Agent, Linked Servers, defaults to encryption mandatory, using the latest security standards—TDS 8.0 and TLS 1.3.
• Configure TLS 1.3 encryption for Always On availability groups, failover cluster instances (FCI), replication, and log shipping with TDS 8.0 support.
• Replication defaults to OLEDB version 19 for inter-instance communication and enforces TLS 1.3 with Encrypt=Strict by default.

Fabric mirroring

• Resource governance can now be used for Fabric Mirroring to isolate and manage resource consumption.
• Dynamic maxtrans configuration option to optimize Fabric mirroring performance

Getting Started

SQL Server 2025 RC0 offers a unique opportunity to explore the latest features via the PREVIEW_FEATURES configuration. These opt-in innovations are designed to foster experimentation and rapid adoption of upcoming capabilities. We encourage all users to review the release notes and take advantage of these powerful new tools.

Accelerating SQL Server 2025 momentum: Announcing the first release candidate

Thank you for being a part of the SQL Server community. Your feedback continues to shape the future of our platform. Download SQL Server 2025 RC0 today and unlock the next era of database excellence!