DaffyDNA

Query your data files with T-SQL, watch every request an application sends to SQL Server, replay that traffic on a test server, and switch servers in the middle of a session, all from one VS Code sidebar.

DaffyDNA brings TroBeeOne's four Daffy tools into VS Code. It installs them, starts them, connects you to them and shows you what they are doing. Without it, that work takes four terminals, a handful of connection strings and the passwords to go with them.

DaffyDNA does nothing to a SQL Server itself. Every action is done by one of the tools, or by Microsoft's SQL Server extension (mssql). Everything DaffyDNA starts listens only on your own machine.

The tools

DaffyDB: your data files, as SQL Server tables

DaffyDB is like Babelfish for PostgreSQL, which lets SQL Server clients work with PostgreSQL, but for DuckDB. It speaks SQL Server's wire protocol and translates T-SQL into DuckDB's SQL. It also answers the catalog queries that SSMS, VS Code and Power BI ask. And it is far smaller: a single .NET tool you start in a folder, with no database server to install.

Behind it is everything DuckDB can read:

• Files. A folder of Parquet, CSV, JSON and Excel files becomes a database of tables. Each file is read where it lies, with nothing to import first.
• Databases. PostgreSQL, MySQL, SQL Server, Azure SQL, SQLite and DuckDB databases mount beside the files, read live and read-only. One query can join last month's Parquet export to a table in PostgreSQL.

In DaffyDNA, DaffyDB is the Warehouse section. There you can:

• add sources in a few prompts;
• see a table's first rows with one click;
• open the warehouse in mssql or Power BI Desktop;
• serve a database from a snapshot instead of the live server;
• export a table, or a whole source, to Parquet.

DaffyTee: see everything an application says to SQL Server

DaffyTee sits between an application and SQL Server or Azure SQL, and records every request it passes on: the SQL, the parameters, the timings and the errors. Neither the application nor the database changes. DaffyTee logs in to the server as an identity you map, so an application that only knows SQL logins can reach a database that expects Entra ID.

In DaffyDNA you can:

• start DaffyTee and add its logins;
• connect mssql through it, or your own application, with a launch configuration DaffyDNA writes for you;
• watch its live dashboard: requests per second, latency from p50 to p99, errors, the statements that take the most time, and a live feed you can click into to see a request's SQL and parameters.

DaffyReplay: replay real traffic, and see what changed

DaffyReplay plays a DaffyTee recording against a test server: as fast as it can, one request at a time, or with the timings as they were recorded. It then reports what fails now that didn't fail before, which row counts changed, and how the timings compare. A raw recording replays at the wire: DaffyReplay sends the same bytes the application sent, including parameter types, prepared statements and bulk loads. Nothing has to be switched on in either database.

In DaffyDNA you can:

• record a workload;
• choose a target, and restore it before each run;
• read each report on its own page;
• compare two runs side by side.

DaffyDuo: one connection, three servers

DaffyDuo gives one client connection up to three SQL Server connections behind it. Connect SSMS, mssql or an application once, and move between servers with one line:

EXEC daffy.connect 'reporting'

Each connection keeps its own session, so a #temp table and the current database are still there when you switch back.

In DaffyDNA you can set DaffyDuo up in a few prompts, switch an editor between personas from the status bar, and see who is connected.

Also in the sidebar

• Connections: one screen listing every SQL Server login that the tools, mssql and DaffyDNA know about, and which tool has which.
• Tools and Health:
  • Tools shows each tool's installed version, with Install and Update.
  • Health checks .NET, the ports, mssql and the certificates, with a Fix button where DaffyDNA can fix it.
• sqlsim Conversion: converts a DaffyTee recording into replay XML for Microsoft's sqlsimtools. It also converts sqlsim's XML into a recording that DaffyReplay can replay.
• A guide, built in: the ? on each section opens its page.
• Agent Skills: one command adds skills that teach GitHub Copilot, Claude Code and other agents to use the tools.

Getting started

You need:

• VS Code 1.105 or later;
• the .NET 10 SDK. If it's missing, DaffyDNA offers to install it (on Windows, through winget).

Microsoft's SQL Server extension (mssql) is recommended: DaffyDNA uses it to run queries.

1. Open a folder, trust it, and click the DaffyDNA icon in the activity bar.
2. In Tools, click Install on each tool you want. Each one is a .NET global tool from NuGet.
3. In Warehouse, click Start, choose a folder of data files, and click a table to see its first 100 rows.

The guide opens by itself the first time DaffyDNA starts, and covers everything else.

Your passwords

SQL Server passwords you save are kept in VS Code's secret storage, encrypted by the operating system.

• Where they go: only to the Daffy tools, on standard input or as a parameter of a tool's admin command. Never on a command line.
• What DaffyDNA never does with them: it never shows or copies a saved password, and never puts one in an mssql or Power BI connection. It never runs anything on a SQL Server itself.

Everything DaffyDNA starts listens on 127.0.0.1 only, and stops when VS Code closes. In a folder you haven't trusted, DaffyDNA starts nothing.

License

DaffyDNA is MIT-licensed. Copyright (c) 2026 TroBeeOne LLC.

The Daffy tools are separate packages that you install from NuGet, and each one keeps its own license:

• DaffyDB is MIT-licensed.
• DaffyTee, DaffyReplay and DaffyDuo are under the Business Source License 1.1. They are free for development and testing, and free in production for personal, academic and non-profit use and for small organizations.

Each package's page has the full terms.

DaffyDNA includes some open-source libraries: Chart.js, markdown-it, and tedious with the Azure libraries it uses. Each keeps its own license, all of them permissive: MIT, ISC, BSD or Apache-2.0. They are listed in THIRD-PARTY-NOTICES.txt.

Protocol and trademarks

DaffyDNA implements nothing of SQL Server. It drives the Daffy tools, which implement the Tabular Data Stream protocol from Microsoft's published MS-TDS specification. DaffyDNA is not affiliated with, endorsed by, or sponsored by Microsoft Corporation, and DaffyDB is not affiliated with Babelfish for PostgreSQL. Microsoft, SQL Server, Azure and Entra are trademarks of Microsoft Corporation.

Contact

TroBeeOne LLC: trobee.one · LinkedIn