Databricks-DE-Pro Data Sharing and Federation Practice Question
A data engineer is using Lakehouse Federation to query data from an external PostgreSQL database. The engineer has created a foreign catalog and foreign schema. Which statement accurately describes how the data is accessed during a query?
⚠ Common exam trap
The trap here is assuming that Lakehouse Federation copies data into Databricks or executes the entire query externally, when it actually uses a hybrid pushdown approach.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The query is translated into PostgreSQL SQL, executed on the external database, and the results are streamed back to Databricks for further processing.
Lakehouse Federation enables querying external databases without copying data. It uses query pushdown to translate and execute parts of the query on the external system, then streams results back to Databricks for any remaining processing. This approach minimizes data movement and leverages the external database's compute. The other options incorrectly describe data copying or full remote execution.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The query is translated into PostgreSQL SQL, executed on the external database, and the results are streamed back to Databricks for further processing.
Why this is correct
Lakehouse Federation uses query pushdown to translate parts of the query into the external database's SQL dialect, executes them remotely, and streams the results back to Databricks. Databricks then performs any remaining operations, such as joins with local data or final aggregations. This minimizes data transfer and leverages the external database's capabilities.
- ✗
The external data is cached in the Databricks workspace's local storage for the duration of the query.
Why it's wrong here
Lakehouse Federation does not cache external data in local storage by default. While some caching may occur at the operating system level, it is not a feature of federation. The data is retrieved on demand from the external source. Caching would introduce staleness and is not part of the federation design.
- ✗
The query is executed entirely within the external PostgreSQL database, and only the results are returned to Databricks.
Why it's wrong here
While Lakehouse Federation pushes down some operations, it does not execute the entire query in the external database. Databricks may perform additional processing, such as joins with local tables or complex aggregations, after retrieving data from the external source. The query is not entirely offloaded; it's a collaborative execution.
- ✗
The data is copied into Delta Lake tables in Unity Catalog before the query runs.
Why it's wrong here
Lakehouse Federation does not copy data into Delta Lake. It enables querying external data in place, without ingestion. Copying data would defeat the purpose of federation, which is to avoid data movement and duplication. The query is pushed down to the external database, and only the results are returned to Databricks.
About these practice questions
This Databricks-DE-Pro question is part of Courseiva's 267-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Databricks exam blueprint
This Databricks-DE-Pro practice question is part of Courseiva's free Databricks certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the Databricks-DE-Pro exam.