A catalogue that only records tables will not answer the questions a security team actually asks: who can see a row, who changed it, and whether an agent is held to the same grant as the analyst sitting next to them.
We considered running our own context store outside Databricks, which would have been quicker, and which would also have meant copying governed data into a second system and then explaining why two permission models existed. Unity Catalog stays the single place access is decided. That is why Fabric runs on it.
What actually breaks
Hive metastore leftovers. Schemas that were never moved because the pipeline already worked. A service principal granted ALL PRIVILEGES for a Thursday demo. Coverage that looks complete in the catalogue browser and stops halfway when you list every schema.
Troy wrote about the lakehouse version of this in Unity Catalog before the first pipeline. The Databricks Health Check is the two-week look: privilege hygiene, orphaned compute, the jobs that should be serverless. Fabric Radar is what we use if we stay to make the interventions governed.
Glue, Purview and BigLake each do a job. The job we are hired for is a Databricks programme where the applications and the agents have to inherit the same grants as a person. Unity Catalog is how that job is even possible. A second catalogue next to it is how it fails.
What we do with it
Catalogue and schema design that matches how the teams actually work. Grants that a security review can read. Lineage that stays intact as data moves. Databricks Apps and agents running under their own service principal, so they cannot reach what they have no grant for. Fabric Harness resolves tools through Unity Catalog for that reason.
If you are standing the lakehouse up, that is the Launchpad: Unity Catalog before the first pipeline. If you already have a workspace and you are not sure the grants hold, start with the Health Check.
Used properly, an audit becomes a query. Used as a sticker on a hive_metastore estate, Unity Catalog is furniture. The Health Check will tell you which one you have.