Microsoft.Data.SqlClient 6.1 Preview 2 has been released. This release contains improvements and updates to the Microsoft.Data.SqlClient data provider for SQL Server.
This 6.1 preview includes a couple of significant additions and many fixes and changes over the 6.1 Preview 1 release (which, if you missed it, had a significant performance increase for async reading of large objects).
Added
Added dedicated SQL Server vector datatype support
What Changed:
- Optimized vector communications between MDS and SQL Server 2025, employing a custom binary format over the TDS protocol. (#3433, #3443)
- Reduced processing load compared to existing JSON-based vector support.
- Initial support for 32-bit single-precision floating point vectors.
Who Benefits:
- Applications moving large vector data sets will see beneficial improvements to processing times and memory requirements.
- Vector-specific APIs are ready to support future numeric representations with a consistent look-and-feel.
Impact:
- Reduced transmission and processing times for vector operations versus JSON using SQL Server 2025 preview:
- Reads: 50x improvement
- Writes: 3.3x improvement
- Bulk Copy: 19x improvement
- (Observed with vector column of max 1998 size, and 10,000 records for each operation.)
- Improved memory footprint due to the elimination of JSON serialization/deserialization and string representation bloat.
- For backwards compatibility with earlier SQL Server Vector implementations, applications may continue to use JSON strings to send/receive vector data, although they will not see any of the performance improvements noted above.
Revived .NET Standard 2.0 target support
What Changed:
- Support for targeting .NET Standard 2.0 has returned. (#3381)
- Support had previously been removed in the 6.0 release, with the [community voicing concerns] (#3115).
Who Benefits:
- Libraries that depend on MDS may seamlessly target any of the following frameworks:
- .NET Standard 2.0
- .NET Framework 4.6.2 and above
- .NET 8.0
- .NET 9.0
- Applications should continue to target runtimes.
- The MDS .NET Standard 2.0 target framework support does not include an actual implementation and cannot be used with a runtime.
- An application's build/publish process should always pick the appropriate MDS .NET/.NET Framework runtime implementation.
- Custom build/publish actions that incorrectly try to deploy the MDS .NET Standard 2.0 reference DLL at runtime are not supported.
Impact:
- Libraries targeting .NET Standard 2.0 will no longer receive warnings like this:
- warning NU1701: Package 'Microsoft.Data.SqlClient 6.0.2' was restored using '.NETFramework,Version=v4.6.1, .NETFramework,Version=v4.6.2, .NETFramework,Version=v4.7, .NETFramework,Version=v4.7.1, .NETFramework,Version=v4.7.2, .NETFramework,Version=v4.8, .NETFramework,Version=v4.8.1' instead of the project target framework '.NETStandard,Version=v2.0'. This package may not be fully compatible with your project.
Fixed
- Fixed missing <NeutralLanguage> property. (#3325)
- Fixed injection of UTF-8 BOM during bulk copy. (#3399)
- Fixed SqlCachedBuffer async read edge case. (#3329)
- Fixed SqlSequentialTextReader edge case with single-byte reads. (#3383)
- Fixed an incorrect error message when parsing connection string PoolBlockingPeriod. (#3411)
- Added missing ToString() override to SqlJson. (#3427)
Changed
- Reduced allocations when opening a connection. (#3364)
- Various performance improvements related to TDS parsing. (#3337, #3377, #3422)
- Improved native AOT support. (#3364, #3369, #3401)
For the full list of changes in Microsoft.Data.SqlClient 6.1 Preview 2, please see the Release Notes.
To try out the new package, add a NuGet reference to Microsoft.Data.SqlClient in your application and pick the 6.1 preview 2 version.
We appreciate the time and effort you spend checking out our previews. It makes the final product that much better. If you encounter any issues or have any feedback, head over to the SqlClient GitHub repository and submit an issue.
David Engel
Microsoft
