Databricks-DE-Pro Data Sharing and Federation Practice Question
A data engineer is using Lakehouse Federation to query an external PostgreSQL database. The engineer creates a connection with the PostgreSQL JDBC URL and credentials, and then creates a foreign catalog. Users report that queries against foreign tables are slow and sometimes fail with connection timeouts. The engineer checks the connection and confirms the credentials are correct. What is the most likely cause of the performance and timeout issues?
⚠ Common exam trap
The trap here is focusing on database configuration or catalog refresh, when the underlying issue is network connectivity between the Databricks cluster and the external database.
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 Databricks cluster lacks the necessary network connectivity to the PostgreSQL database, causing timeouts.
Lakehouse Federation queries run on Databricks compute, which must connect to the external database over the network. If the cluster cannot reach the database due to network restrictions, queries will be slow or time out. Ensuring proper network connectivity, such as VPC peering or firewall rules, is essential for reliable federation.
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 foreign catalog is not configured with a read-only mode, causing write attempts that time out.
Why it's wrong here
Foreign catalogs are read-only by design for Lakehouse Federation. There is no write mode that would cause timeouts. The issue is likely related to network or resource constraints, not write attempts. Configuring read-only mode is not applicable because it is already enforced.
- ✗
The foreign catalog must be refreshed to update statistics, causing slow queries.
Why it's wrong here
Refreshing a foreign catalog updates metadata about schemas and tables, but it does not affect query performance directly. Slow queries and timeouts are more likely due to network or database load. While statistics can impact query planning, the timeouts suggest a connectivity issue.
- ✓
The Databricks cluster lacks the necessary network connectivity to the PostgreSQL database, causing timeouts.
Why this is correct
Lakehouse Federation queries are executed by the Databricks cluster, which must have network access to the external database. If the cluster is in a VPC without proper peering or firewall rules, connections may be slow or time out. Ensuring network connectivity, such as VPC peering or allowing Databricks IPs, is crucial for performance and reliability.
- ✗
The PostgreSQL database is not configured with the correct Unity Catalog connection parameters.
Why it's wrong here
If the connection parameters were incorrect, the connection would fail entirely, not just be slow. The engineer confirmed credentials are correct, so the connection is established. The issue is intermittent timeouts, which point to network latency or resource contention rather than misconfiguration.
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.