POST_START

Using the Catalog.Schema.Object Three-Level Namespace in Databricks Unity Catalog

I recently started working on a new project in Databricks that involves organizing data assets using the Unity Catalog. One of the key concepts I needed to understand was the three-level namespace: Catalog.Schema.Object. I wanted to explore how to navigate and access objects using this structure. To do that, I followed a set of steps provided in the curriculum, which focused on using the training catalog and the sales schema.

Starting with the Catalog

I began by switching to the training catalog. This is the top-level namespace that contains all the schemas and objects I have access to. I ran the following command:

USE CATALOG training;

I saw a representative result like this:

I noticed that the command completed successfully, which means I was now working within the training catalog. This is the first step in navigating the three-level namespace.

Switching to the Schema

Next, I wanted to explore the sales schema within the training catalog. I executed the following command:

USE SCHEMA sales;

I saw a representative result like this:

This confirmed that I had successfully switched to the sales schema. Now, I was ready to query objects within this schema.

Querying the Object

I decided to start by querying the customers table. Since I was already in the sales schema, I could refer to the table directly:

SELECT * FROM customers;

I saw a representative result like this:

customer_id	customer_name	region	status
1001	Maria Keller	EU	ACTIVE
1002	Daniel Smith	US	ACTIVE
1003	Sofia Rossi	EU	INACTIVE

I learned that the customers table contains basic information about customers, such as their ID, name, region, and status. This gave me a clear view of the data structure.

Accessing the Object with the Full Namespace

To ensure I understood how the three-level namespace works, I decided to query the customers table using the full training.sales namespace:

SELECT * FROM training.sales.customers;

I saw a representative result like this:

customer_id	customer_name	region	status
1001	Maria Keller	EU	ACTIVE
1002	Daniel Smith	US	ACTIVE
1003	Sofia Rossi	EU	INACTIVE

This confirmed that I could access the table using the full three-level namespace. It reinforced the structure of the Unity Catalog and how it organizes data assets.

Conclusion

By following these steps, I gained a solid understanding of how to navigate and access objects within the Unity Catalog using the three-level namespace. I learned that the CATALOG, SCHEMA, and OBJECT levels are essential for organizing and querying data in a structured way. This knowledge will help me work more efficiently with data in Databricks.