A bank’s credit-risk reporting team needs one change before the monthly committee pack. The underlying exposure data is current. The semantic model can reach it. The requested change—reclassifying a set of delinquency bands—is not particularly difficult.
Yet the team that owns the report cannot publish the change. The curated table is maintained by a Spark process owned elsewhere, so the request becomes a ticket, a handoff, and a negotiation over another team’s release calendar. Nothing in Microsoft Fabric is broken. The architecture treated the point where data was published as a storage destination when it was really a contract with an owner.
The reverse failure is just as common. A data-engineering team already publishes well-governed Delta tables for analytics, data science, and downstream domains, but an architectural standard requires every Gold table to be copied into a Warehouse before Power BI can use it. The second published copy adds another load, another security boundary, another incident path, and another opportunity for the two versions to disagree. It exists because a diagram said Gold should look like a database.
Fabric Warehouse and Lakehouse overlap too much for the old rule—structured data goes to a warehouse; everything else goes to a lakehouse—to make this decision well. Both use Delta in OneLake. Both can serve SQL queries. Both can support Power BI and governed analytical products. The consequential difference is the publication contract each item is being asked to own and the team expected to keep it.
Choose a Lakehouse publication contract when the authoritative product is maintained as Delta through engineering workflows and SQL consumers primarily need to read it. Choose a Warehouse publication contract when the owning team must create, populate, correct, secure, and release a relational product through T-SQL, especially when multi-table transactions or an independent SQL-owned release cadence matter. Use both when two real contracts exist—not because one Fabric icon feels unfinished without the other.
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