DEA-C01 Data Ingestion and Transformation Practice Question
A data engineer must load a 50 GB uncompressed CSV file from Amazon S3 into an Amazon Redshift cluster using the COPY command. The load is taking a long time and the engineer wants to improve performance. Which action should the engineer take?
⚠ Common exam trap
The trap here is believing that adding cluster nodes automatically speeds up loading a single large file.
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
✓
Compress the file with gzip and split it into multiple smaller files, then run the COPY command with the GZIP option.
Redshift COPY performance depends on parallelizing reads across slices and minimizing bytes transferred. Compressing the CSV with gzip reduces transfer volume, and splitting it into multiple files lets each slice load a portion concurrently. The GZIP parameter handles decompression during ingest. A single large uncompressed file limits parallelism regardless of cluster size.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Convert the CSV file to JSON and load it with the COPY command using the JSON 'auto' option.
Why it's wrong here
Converting to JSON does not inherently speed up loading and may increase file size and parsing overhead. The COPY command supports JSON, but the format change does not address the core bottleneck of a single large uncompressed file being read sequentially. Compression and file splitting are the relevant optimizations.
- ✓
Compress the file with gzip and split it into multiple smaller files, then run the COPY command with the GZIP option.
Why this is correct
Compressing the data reduces the bytes transferred from Amazon S3 and splitting the file into multiple parts lets Redshift load slices in parallel across the cluster. The COPY command supports the GZIP parameter to decompress on ingest. Together these changes dramatically reduce load time compared with a single large uncompressed file.
- ✗
Use the COPY command with the PARALLEL OFF option to force Redshift to distribute the load across all slices.
Why it's wrong here
PARALLEL OFF disables parallel loading and forces Redshift to load data serially from a single file. This is the opposite of what is needed and would make the load slower, not faster. The option is intended for cases where serial loading is required, such as when loading from certain file formats.
- ✗
Increase the cluster's node count and rerun the COPY command on the same single uncompressed file.
Why it's wrong here
Adding nodes increases available compute and storage, but a single uncompressed file cannot be parallelized effectively across slices. Redshift loads a single file through one slice, so extra nodes sit idle during the load. Without splitting or compressing the file, the bottleneck remains the sequential read of one large object.
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 |
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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 Amazon Web Services exam blueprint
This DEA-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 DEA-C01 exam.