Unity Catalog
Finance reads bronze because gold grants were missing
Symptoms
- Workspace members saw everything in hive_metastore
- UC gold had no SELECT
Unity Catalog interview questions
Interactive Databricks interview questions on Unity Catalog. Same topic as /learn/databricks/unity-catalog. catalog.schema.table with metastore-level governance, privileges, and lineage — not hive_metastore.default.
Question 1 of 3
beginner
Unity CatalogWhat is Unity Catalog's three-level namespace?
Answer it out loud, then reveal. Play steps through like the simulators.
Production scenario
Case 1 of 1 · symptoms
All questions on this page
Indexed as FAQ. Open any item if you prefer a list to Play.
beginnerWhat is Unity Catalog's three-level namespace?
Unity Catalog · tap to open the answer
Short: catalog.schema.table (plus volumes for files).
Detailed: It is the governance plane: grants, lineage, audit. Table files still live in cloud storage. hive_metastore is the old two-level world.
Common mistake: Unity Catalog as a replacement for Delta files.
Follow-up: Where do you grant SELECT — catalog, schema, or table?
intermediateA user can see a table in the UI but Spark says permission denied. Why?
Unity Catalog · tap to open the answer
Short: Workspace access ≠ UC privilege on that catalog/schema/table.
Detailed: They need USE CATALOG, USE SCHEMA, and SELECT (or a share). Cluster must be UC-enabled. A personal compute with the wrong catalog still fails.
Common mistake: Making the table public because 'they're in the workspace'.
Follow-up: What's the difference between a storage credential and an external location?
seniorHow do you share a gold table with another cloud account without copying files?
Unity Catalog · tap to open the answer
Short: Delta Sharing / UC shares — grants on a share, not a second lake.
Detailed: Recipient gets access through the sharing protocol. Your storage stays. Don't clone PII into their bucket 'to make BI easy'. Lineage should show the share.
Senior: The files. UC stores metadata and grants; the bytes stay in the owner’s storage unless you explicitly copy.
Common mistake: COPY INTO their account as the default share mechanism.
Follow-up: What must still live in the data plane?