Why Every Power BI Developer Should Be Using TMDL — Explained by the PM Behind It

Most Power BI developers still do all of their modeling through the UI. And there is nothing wrong with that — until you hit the things the UI cannot do efficiently. TMDL — Tabular Model Definition Language — changes that. In this short clip from my Fabric Insider Ep. 5 interview with Christian Wade, Principal PM Architect for Power BI Semantic Models at Microsoft, we go through exactly what TMDL gives you and why it is worth switching to. Here is what TMDL in the browser gives you that the UI simply cannot match: 📝 Your entire semantic model definition — tables, columns, measures, relationships, translations — all in one readable script ✏️ Bulk edits across the entire model — no clicking through dialog boxes one by one 🌍 Multilingual translations — Spanish, French, Brazilian Portuguese — all visible and editable in one view 💬 Business definitions written directly in the script — appear inside the semantic model automatically 🖥️ Full VS Code IDE embedded in the browser — breadcrumbs, scrollbar, intellisense, all developer-grade tooling 🤖 Open the Power BI Project in VS Code and use GitHub Copilot to generate TMDL — it is, as Christian put it, "freaking amazing" And the big picture takeaway: the DAX in a TMDL script is dramatically more expressive than an equivalent SQL definition would be. The same business calculations that would take thousands of lines in SQL — written concisely and clearly in DAX inside TMDL. 📺 Full Fabric Insider Ep. 5 interview with Christian Wade: https://www.youtube.com/watch?v=zndWuBB1JTo 📝 Full blog post: https://radacad.com/whats-hot-and-new-for-power-bi-semantic-models-in-2026-a-conversation-with-christian-wade-fabric-insider-ep-5/ 🎬 Full Fabric Insider Playlist: https://www.youtube.com/playlist?list=PLMXQvYI7QV6f8vUxtlFuGzQk-tYj3uOTn 🎧 Fabric Insider on Spotify: https://open.spotify.com/show/4eJrCr5UOWZ7ggmrVUce6l?si=Jx18sgdaScCgR3P1oDz-dw 💡 Power BI / Fabric Ideas: https://ideas.fabric.microsoft.com 💬 Microsoft Fabric Reddit: https://www.reddit.com/r/MicrosoftFabric/ 🔗 Christian Wade on LinkedIn: https://www.linkedin.com/in/christianwade1/ 🌐 RADACAD: https://radacad.com 🔗 Corporate Training: https://radacad.com/corporate-training/ 🔗 Power BI Training: https://radacad.com/power-bi-training/ 🔗 Microsoft Fabric Training: https://radacad.com/microsoft-fabric-training/ #PowerBI #TMDL #SemanticModel #PowerBIDesktop #PowerBIDeveloper #MicrosoftFabric #FabricInsider #ChristianWade #GitHubCopilot #VSCode #DataModeling #BusinessIntelligence #DAX #PowerBITips #FabricAnalytics