Databricks-DE-Assoc Troubleshooting, Monitoring, and Optimization Practice Question
A data engineer is optimizing a Delta table that suffers from slow read performance due to small file sizes. Which command should the engineer execute to consolidate these small files into larger, more efficient files without altering the underlying table data?
⚠ Common exam trap
Candidates often select 'VACUUM' because it is a common maintenance command. However, VACUUM deletes files rather than consolidating them, which would not solve a small file performance issue.
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
✓
OPTIMIZE table_name
The OPTIMIZE command is specifically designed for compacting small files into larger ones, which improves read performance by reducing metadata overhead and increasing scan efficiency. This operation is essential in Databricks environments where frequent streaming or batch writes create many small files, leading to 'small file syndrome.' By restructuring the data files while maintaining the table's logical state, OPTIMIZE ensures that downstream queries scan fewer, more optimized data blocks.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
ALTER TABLE table_name REORGANIZE
Why it's wrong here
REORGANIZE is used for rewriting data to fix issues like data layout or column mapping changes, but it is not the primary command for file compaction. While it performs some rewrites, OPTIMIZE is the purpose-built DML operation for file management and Z-Ordering features in Delta Lake tables.
- ✓
OPTIMIZE table_name
Why this is correct
The OPTIMIZE command packs small files into larger ones to improve scan speed. It leverages Delta Lake's file-level metadata to identify small files and rewrite them into larger, optimized files. This is the standard practice for maintaining performance in tables that receive frequent small write operations.
- ✗
VACUUM table_name
Why it's wrong here
VACUUM removes physical data files that are no longer referenced by the Delta log and are older than a specified retention threshold. It does not consolidate files to improve read performance; instead, it is a maintenance operation used to reduce storage costs and satisfy data privacy requirements.
- ✗
ANALYZE TABLE table_name COMPUTE STATISTICS
Why it's wrong here
ANALYZE TABLE generates statistics used by the Databricks cost-based optimizer to create efficient query plans. While it improves query performance by helping the optimizer choose better join strategies and scan paths, it does not physically consolidate small files or change the underlying file structure on disk.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Databricks exam blueprint
This Databricks-DE-Assoc practice question is part of Courseiva's free Databricks 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 Databricks-DE-Assoc exam.