DEA-C01 Data Operations and Support Practice Question
A company uses Amazon S3 to store raw data and AWS Glue to run ETL jobs. The data is partitioned by date in the format 'year=YYYY/month=MM/day=DD'. A new data source started sending data with a different date format 'YYYY-MM-DD'. The Glue crawler is configured to create a single table for the entire bucket. The crawler runs daily, but it is not detecting the new partitions from the new data source. The existing partitions are in the format 'year=2024/month=05/day=10', while the new data is stored as '2024-05-10/' without the key-value structure. How should the engineer modify the data pipeline to include the new data?
⚠ Common exam trap
The trap is thinking that a crawler configuration change (like custom classifiers or partition indexes) can handle non-standard partition formats; actually, the data must be stored in a compatible format for automatic detection.
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
✓
Modify the new data source to store data in the same Hive-style partition format as the existing data.
The AWS Glue crawler relies on Hive-style partitioning (e.g., 'year=YYYY/month=MM/day=DD') to automatically detect and create partitions. The new data source uses a different format ('YYYY-MM-DD/') that does not follow the key-value structure, so the crawler cannot recognize it as partitions. The engineer must modify the new data source to store data in the same Hive-style partition format as the existing data.
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 crawler with the 'Create partition indexes' option enabled.
Why it's wrong here
Partition indexes accelerate crawler and query metadata lookups but cannot reconcile two incompatible S3 key layouts. The crawler infers partitions from key=value prefixes, so the new YYYY-MM-DD paths need separate handling, such as a distinct table or transformed keys.
- ✗
Configure the crawler to add a custom classifier for date formats.
Why it's wrong here
Custom classifiers parse record contents, not S3 key path structure, so they cannot make the crawler recognise '2024-05-10/' as a Hive-style partition. A classifier is the correct tool when incoming files use a non-standard record format, such as a bespoke log or CSV layout, that the crawler must interpret.
- ✓
Modify the new data source to store data in the same Hive-style partition format as the existing data.
Why this is correct
Hive-style partitioning requires the key=value directory structure that Glue's crawler parses to infer partition columns. The new source's flat 'YYYY-MM-DD/' folders lack that structure, so the crawler cannot register them as partitions. Conforming the new data to 'year=YYYY/month=MM/day=DD' satisfies the single-table constraint and restores daily partition detection.
- ✗
Convert the new data to Parquet format.
Why it's wrong here
Parquet is a columnar storage format, not a partition-discovery mechanism; the crawler fails because the new keys lack the year=/month=/day= structure, and rewriting files as Parquet leaves that path layout unchanged. Parquet would be the right choice when the goal is reducing scan cost and improving query performance.
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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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.