DBS-C01 Workload-Specific Database Design Practice Question
A company runs a reporting application on Amazon Redshift. The application queries a large fact table that is distributed by a key. The report queries filter on a date column. The report performance is slow. The database has 10 nodes. The company wants to improve query performance by optimizing the table design. Which design change should be made?
⚠ Common exam trap
A common mix-up: candidates confuse the purpose of distribution keys (for join co-location) with sort keys (for filter pruning), leading them to choose distribution changes (options C or D) instead of the correct sort key optimization.
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
✓
Set the sort key to the date column.
Setting the sort key to the date column improves query performance by enabling range-restricted scans. When queries filter on a date column, Redshift uses zone maps to skip blocks that do not contain relevant data, drastically reducing the number of rows scanned. This is the most direct and cost-effective optimization for filter-heavy workloads on large fact tables.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Set the sort key to the date column.
Why this is correct
Sort keys enable efficient range filtering, improving query performance for date-based filters.
- ✗
Increase the number of nodes in the cluster.
Why it's wrong here
Adding nodes may help parallelism but does not optimize the table design.
- ✗
Change the distribution style to ALL to avoid data redistribution.
Why it's wrong here
ALL distribution copies the table to all nodes, which is not ideal for large fact tables.
- ✗
Change the distribution style to KEY on the date column.
Why it's wrong here
Distributing by date may cause data skew if dates are not evenly distributed.
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This DBS-C01 practice question is part of Courseiva's free Amazon Web Services 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 DBS-C01 exam.