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Troubleshooting Unexpected Row-Level Access Results from Unity Catalog Row Filters

I was working on a query against the production.sales.customers table and noticed that some rows were not being returned as expected. I suspected that Unity Catalog row filters might be at play, but I wasn’t sure why the results didn’t align with what I expected. I decided to investigate by first understanding the metadata and access controls in place.

Checking the Table Metadata

I started by running the DESCRIBE TABLE EXTENDED command to get detailed metadata about the production.sales.customers table. This would help me confirm if any row-level security policies or filters were defined.

DESCRIBE TABLE EXTENDED production.sales.customers;

The output showed that the table was managed by Unity Catalog and had several properties, including owner, storage, and rowLevelSecurity set to true. This confirmed that row-level access controls were in effect. However, the output didn’t clearly explain which rows were being filtered out, so I needed to dig deeper.

Verifying My Current User Context

I realized that the row filters might depend on the current user’s identity and permissions. To ensure I was working with the correct context, I ran the SELECT current_user() command.

SELECT current_user();

The result showed that I was logged in as user@domain.com, which was the same user I had been using throughout my session. This indicated that my user context was consistent, so the issue was likely not related to authentication or user switching.

Testing the Query with Full Data Access

Next, I decided to run a simple SELECT * FROM production.sales.customers to see what data was actually being returned. This would help me understand the scope of the row filters and whether the unexpected results were due to access restrictions.

SELECT * FROM production.sales.customers;

The query returned fewer rows than I expected. I was puzzled because I had assumed the table was fully accessible to me. I began to suspect that the row filters were not just based on my user privileges, but also on specific conditions defined in the Unity Catalog policies.

Re-evaluating the Row-Level Filters

With the query results in hand, I revisited the table metadata to see if there were any additional details about the row filters. I noticed a rowFilter property that pointed to a specific policy definition. This was a clue that I needed to check the policy itself to understand why certain rows were being excluded.

I realized that the policy might be filtering rows based on the region or account_id columns, which I hadn’t considered in my initial query. I planned to test this hypothesis by querying the table with additional filters to see if the results aligned with the expected behavior.

In the next step, I would need to either adjust the policy or modify my query to account for the row-level access rules. But first, I needed to confirm exactly which rows were being excluded and why.