DP-700 Monitor and Optimize an Analytics Solution Practice Question
Your team is using a Fabric Lakehouse to store Parquet files. You notice that the storage costs are increasing faster than expected, and there are many old versions of the data being retained. Which maintenance task should you schedule to optimize OneLake storage costs without affecting the current production data?
⚠ Common exam trap
Candidates often choose 'OPTIMIZE' or 'Partitioning'. These improve performance but do not delete the old files causing high storage costs. Only the VACUUM command removes unreferenced files to reclaim space.
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 on the Delta tables.
Delta tables in Fabric maintain a history of changes to support features like 'Time Travel'. However, this history consumes storage space over time as old, unreferenced Parquet files are kept. The VACUUM command is the standard maintenance operation to permanently delete these old files, balancing historical data needs with storage efficiency.
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 OPTIMIZE command on all tables.
Why it's wrong here
The OPTIMIZE command improves query performance by compacting small files and applying V-Order. While it makes data access faster, it actually creates new files and keeps the old ones for a period of time, which can temporarily increase storage usage rather than decreasing it immediately.
- ✓
Run the VACUUM command on the Delta tables.
Why this is correct
The VACUUM command removes data files that are no longer referenced by a Delta table and are older than a specified retention threshold. By cleaning up these legacy files, you reduce the total storage footprint in OneLake, which directly lowers the associated storage costs for the workspace.
- ✗
Change the workspace license to 'Pro'.
Why it's wrong here
Changing a workspace license to Pro would disable most Fabric features like Lakehouses and Spark notebooks, as these require a Fabric Capacity or Premium per User (PPU) license. This is not a valid strategy for optimizing storage while maintaining the existing analytical workload and data architecture.
- ✗
Delete the '_delta_log' folder in OneLake.
Why it's wrong here
Deleting the '_delta_log' folder would corrupt the Delta table, as this folder contains the transaction log that tracks all changes and file references. Without this log, the data files in the folder are just disconnected Parquet files, and the table would become unreadable by Fabric engines.
About these practice questions
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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 Microsoft exam blueprint
This DP-700 practice question is part of Courseiva's free Microsoft 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 DP-700 exam.