- A
DESCRIBE HISTORY delta_table;
Why wrong: DESCRIBE HISTORY only shows the table's version history, it does not clean up old files.
- B
VACUUM delta_table RETAIN 30 HOURS;
VACUUM is the right command, but the retention parameter must be set to 30 DAYS, not 30 HOURS, to fulfill the 30-day requirement.
- C
OPTIMIZE delta_table;
Why wrong: OPTIMIZE compacts small files into larger ones but does not delete old versions.
- D
FSCK REPAIR TABLE delta_table;
Why wrong: FSCK REPAIR TABLE recovers metadata inconsistencies but does not affect file retention for time travel.
Question 512 of 851
DP-203 VACUUM Practice Question
This DP-203 practice question tests your understanding of monitor and optimize data storage and processing. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. A key principle to apply: vACUUM. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Your team uses Azure Databricks with Delta Lake for ETL. You notice that the Delta table's version history is growing rapidly, and query performance is degrading. You want to retain the ability to time travel for the last 30 days. Which Delta Lake command should you run?
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
✓
VACUUM delta_table RETAIN 30 HOURS;
None of the provided options is correct for retaining time travel capability for 30 days. The correct Delta Lake command is `VACUUM delta_table RETAIN 30 DAYS`. Option B incorrectly specifies `30 HOURS`, which retains only 30 hours. DESCRIBE HISTORY, OPTIMIZE, and FSCK REPAIR TABLE do not remove old versions to free space.
Key principle: VACUUM
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
DESCRIBE HISTORY delta_table;
Why it's wrong here
DESCRIBE HISTORY only shows the table's version history, it does not clean up old files.
- ✓
VACUUM delta_table RETAIN 30 HOURS;
Why this is correct
VACUUM is the right command, but the retention parameter must be set to 30 DAYS, not 30 HOURS, to fulfill the 30-day requirement.
Related concept
VACUUM
- ✗
OPTIMIZE delta_table;
Why it's wrong here
OPTIMIZE compacts small files into larger ones but does not delete old versions.
- ✗
FSCK REPAIR TABLE delta_table;
Why it's wrong here
FSCK REPAIR TABLE recovers metadata inconsistencies but does not affect file retention for time travel.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Candidates often confuse VACUUM's retention parameter with days instead of hours, or mistakenly think OPTIMIZE removes old versions when it only compacts files.
Trap categories for this question
Command / output trap
DESCRIBE HISTORY only shows the table's version history, it does not clean up old files.
Detailed technical explanation
How to think about this question
Under the hood, VACUUM uses the Delta transaction log to identify files that are no longer referenced by any table version within the retention window, then deletes them from the underlying file system (e.g., ADLS Gen2 or S3). A subtle behavior is that VACUUM by default retains 7 days (168 hours), so specifying 30 HOURS (not days) is a deliberate trap—candidates must carefully read the unit. In real-world scenarios, if you set retention too low (e.g., 0 hours), you lose time travel capability entirely, which can break audit or rollback requirements.
KKey Concepts to Remember
- VACUUM
- Time Travel
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
VACUUM
Real-world example
How this comes up in practice
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. VACUUM Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Review vACUUM, then practise related DP-203 questions on the same topic to reinforce the concept.
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FAQ
Questions learners often ask
What does this DP-203 question test?
Monitor and optimize data storage and processing — This question tests Monitor and optimize data storage and processing — VACUUM.
What is the correct answer to this question?
The correct answer is: VACUUM delta_table RETAIN 30 HOURS; — None of the provided options is correct for retaining time travel capability for 30 days. The correct Delta Lake command is `VACUUM delta_table RETAIN 30 DAYS`. Option B incorrectly specifies `30 HOURS`, which retains only 30 hours. DESCRIBE HISTORY, OPTIMIZE, and FSCK REPAIR TABLE do not remove old versions to free space.
What should I do if I get this DP-203 question wrong?
Review vACUUM, then practise related DP-203 questions on the same topic to reinforce the concept.
What is the key concept behind this question?
VACUUM
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Last reviewed: Jun 11, 2026
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