Modernizing the Semantic Layer Spec
New engine, who dis?
It’s unlikely that anyone reading this blog has not heard about the new dbt Fusion engine — it’s been the talk of the data town since last January, culminating in Elias’s legendary live Coalesce 2025 demo of the incredible capabilities that native SQL comprehension in dbt can unlock. If you attended Coalesce, or have upgraded your project to Fusion already, you’ve likely also heard about the changes we’ve made to the authoring layer of dbt (the literal code you write in your project). As part of the major version upgrade, we took the opportunity to simplify + standardize the configuration language of dbt to be built to scale as we enter the next era of analytics engineering.
In particular, we wanted to reevaluate how metrics are defined in the dbt Semantic Layer. We’ve heard from numerous community members over the years that defining metrics was just plain hard. In conversation with internal + external users and our newest pals from SDF, we’ve come up with a redesigned YAML spec that is simpler, more integrated to the dbt configuration experience we’ve come to know and love, and built for the future.


















