PCDE Plan and manage database infrastructure Practice Question
A company runs a BigQuery data warehouse. They notice that query performance has degraded over time. The data is loaded daily from Cloud Storage using batch loads. Which action is most likely to improve query performance?
⚠ Common exam trap
Google Cloud often tests the misconception that adding more compute resources (slots) is the default fix for slow queries, when in reality data organization techniques like partitioning and clustering are the first-line optimization for scan-heavy workloads.
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
✓
Partition and cluster tables based on common query filters.
Partitioning and clustering tables based on common query filters directly reduces the amount of data scanned per query by organizing data into physical segments. In BigQuery, this allows the query engine to prune entire partitions and clusters, significantly lowering I/O and improving performance without additional cost or complexity.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Partition and cluster tables based on common query filters.
Why this is correct
Partitioning and clustering reduce data scanned, improving performance.
- ✗
Increase the number of slots in the reservation.
Why it's wrong here
More slots help concurrency but not per-query scan efficiency.
- ✗
Create materialized views for all frequent queries.
Why it's wrong here
Materialized views can help but are not the first diagnostic or optimization step.
- ✗
Migrate the data to Cloud SQL for better performance.
Why it's wrong here
Cloud SQL is not designed for OLAP workloads.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PCDE practice question is part of Courseiva's free Google Cloud 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 PCDE exam.