MLS-C01 Data Engineering Practice Question
A company uses Amazon Redshift to run analytics on sales data. The data is loaded daily from S3 using COPY commands. The team notices that the COPY command performance degrades over time due to table bloat. The team needs to maintain query performance and reduce storage costs. Which combination of maintenance operations should the team perform regularly? (Choose THREE.)
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
✓
Run the VACUUM command to reclaim space and re-sort rows.
The correct maintenance operations are VACUUM, DEEP COPY, and ANALYZE. VACUUM reclaims space from deleted or updated rows and re-sorts data if sort keys are defined, reducing bloat. DEEP COPY recreates the table to eliminate bloat completely by copying data to a new table and renaming. ANALYZE updates table statistics, which helps the query planner optimize query performance. Option A (UNLOAD) is wrong because it exports data to S3, not a maintenance operation. Option B (changing distribution style) is a schema change that affects data distribution, not a regular maintenance task for bloat removal.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Run the UNLOAD command to export data to S3 and then reload.
Why it's wrong here
UNLOAD is for exporting, not for maintenance.
- ✗
Change the distribution style of the table to KEY.
Why it's wrong here
Changing distribution style is a schema modification, not a maintenance operation.
- ✓
Run the VACUUM command to reclaim space and re-sort rows.
Why this is correct
VACUUM removes deleted rows and re-sorts data.
- ✓
Run a DEEP COPY to recreate the table with optimal physical storage.
Why this is correct
DEEP COPY eliminates bloat by creating a new table.
- ✓
Run the ANALYZE command to update table statistics.
Why this is correct
ANALYZE ensures the query optimizer has up-to-date statistics.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
Go deeper
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This MLS-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 MLS-C01 exam.