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Extension descriptor (YAML)

Connect DuckDB to Microsoft SQL Server via native TDS (including TLS).

Compatibility Matrix

This table covers all DuckDB releases that have not reached end-of-life, including LTS releases, and shows the 2 most recent patch releases of each. Older patch releases are not listed, but the extension may be available for them as well.

Installing and Loading

INSTALL mssql FROM community;
LOAD mssql;

Example

INSTALL mssql FROM community;
LOAD mssql;
ATTACH 'Server=localhost,1433;Database=master;User Id=sa;Password=YourStrong!Passw0rd;TrustServerCertificate=yes' AS ms (TYPE mssql);
SELECT * FROM ms.dbo.your_table LIMIT 5;

About mssql

DuckDB connector for Microsoft SQL Server, Azure SQL and Microsoft Fabric over a native TDS 7.4 implementation — no ODBC, JDBC or FreeTDS required. Attach a server as a DuckDB catalog and query, join, and bulk-load it alongside your local data.

Documentation: https://hugr-lab.com/docs/mssql-extension/

Reading. Attached tables come with schema/table catalog integration and a lazily loaded metadata cache. A SELECT the extension can write in T-SQL — joins, aggregates, GROUP BY, window functions, ORDER BY / LIMIT, subqueries, CTEs — runs on SQL Server as one statement (EXPLAIN shows it); the rest streams through projection and filter pushdown and a columnar, batch-decoded result path.

Writing. COPY TO, CTAS and large INSERTs ship over the BCP bulk-load protocol with up to 8 parallel sessions. UPDATE, DELETE, INSERT … SELECT and MERGE run on the server as one statement when they can be written in T-SQL, and through a session staging table otherwise — no primary key required, RETURNING supported. DuckDB transactions map to SQL Server transactions on one pinned connection.

Authentication and security. SQL logins, Azure Entra ID (Service Principal, CLI, Device Code), Kerberos on POSIX, Windows SSPI, DuckDB secrets; TLS with the server certificate verified by default.

Operations. Per-catalog connection pooling, eager ATTACH-time credential validation, named-instance resolution via SQL Server Browser, custom Application Name.

Issues and feature requests: https://github.com/hugr-lab/mssql-extension

Added Functions

Overloaded Functions

This extension does not add any function overloads.

Added Types

Added Settings