Databricks UC: How to migrate from a 2-part namespace to a 3-part namespace.

One significant change when migrating from Hive Metastore to Unity Catalog is changing PySpark / SQL from 2 namespaces to 3 namespaces.

Src: Image by DallE

Hive Metastore uses two namespaces, and Unity Catalog uses three namespaces.

In Hive Metastore (HMS)

select * from database.table