DEA-C02 Data Movement Practice Question
An organization is unloading data from a Snowflake table to an external S3 bucket for use in a machine learning pipeline. Which TWO practices will optimize the performance and manageability of the exported files? (Select TWO)
⚠ Common exam trap
Candidates often choose 'file compression' or 'warehouse size' as the primary optimization for unloading. However, file size and folder structure are more critical for downstream read performance.
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
✓
Use the PARTITION BY clause in the COPY INTO <location> statement to organize files into subfolders.
Optimizing data unloading requires balancing file size and organizational structure. Using the PARTITION BY clause ensures that the exported files are organized into a logical folder hierarchy, which facilitates faster data discovery for downstream tools. Additionally, controlling the MAX_FILE_SIZE ensures that the files are not too large for the consuming application to process efficiently in memory while maintaining parallelism.
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 SINGLE parameter to TRUE to ensure all data is consolidated into one large file.
Why it's wrong here
Setting SINGLE to TRUE disables parallel execution during the unload process. This forces the entire dataset to be processed by a single thread, which significantly increases the time required to export large tables and eliminates the performance benefits provided by the distributed architecture of the Snowflake virtual warehouse.
- ✓
Use the PARTITION BY clause in the COPY INTO <location> statement to organize files into subfolders.
Why this is correct
The PARTITION BY clause allows engineers to dynamically create a directory structure in the external stage based on column values. This improves the performance of downstream applications that only need to read specific subsets of data and helps maintain a clean, navigable data lake environment for long-term storage.
- ✗
Disable compression using the COMPRESSION = NONE parameter to reduce the CPU load on the warehouse.
Why it's wrong here
While disabling compression might slightly reduce CPU usage, it significantly increases the volume of data transferred over the network and the storage costs in the S3 bucket. Most modern data tools prefer compressed formats like GZIP, and the overhead of compression is usually negligible compared to the network I/O savings.
- ✓
Configure the MAX_FILE_SIZE parameter to generate files that are roughly 100MB to 250MB in size.
Why this is correct
Generating files in the 100MB to 250MB range strikes a balance between having too many small files, which causes metadata overhead, and having few large files, which limits parallel processing. This size range is ideal for most cloud storage systems and downstream distributed processing frameworks like Spark or Snowflake's own COPY command.
- ✗
Always use the OVERWRITE = TRUE parameter to prevent the command from failing if files already exist.
Why it's wrong here
While OVERWRITE can prevent errors, it is not a performance optimization and can be dangerous in production environments. If used incorrectly, it can lead to accidental data loss by overwriting existing exports that might still be needed by other processes, making it a management risk rather than a best practice for optimization.
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 |
About these practice questions
This DEA-C02 question is part of Courseiva's 229-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
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 Snowflake exam blueprint
This DEA-C02 practice question is part of Courseiva's free Snowflake 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 DEA-C02 exam.