DEA-C01 Data Ingestion and Transformation Practice Question
A company has a Glue ETL job that reads from an Amazon RDS for MySQL table and writes to Amazon S3. The job runs hourly and processes new records based on a 'last_modified' timestamp column. Recently, the job started missing some records because the timestamp in MySQL is stored with microsecond precision but Glue's job bookmark only tracks second precision. Which solution addresses this issue?
⚠ Common exam trap
It's easy for candidates to assume Glue job bookmarks automatically handle all timestamp precisions, but the exam tests awareness that bookmarks default to second-level granularity and that custom logic is required for sub-second precision.
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 a job parameter to store the last processed timestamp with millisecond precision and query records greater than that value.
AWS Glue job bookmarks track timestamps with only second precision, so records with microsecond differences within the same second are missed. By using a custom job parameter to store the last processed timestamp with millisecond precision and querying records greater than that value, you bypass Glue's bookmark limitation and capture all new or modified records.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Use a job parameter to store the last processed timestamp with millisecond precision and query records greater than that value.
Why this is correct
Custom job bookmark with higher precision.
- ✗
Increase the job frequency to every 30 minutes.
Why it's wrong here
Does not solve the precision problem.
- ✗
Run a full refresh of the table each time instead of incremental.
Why it's wrong here
Inefficient and not recommended.
- ✗
Modify the MySQL table to use a DATE data type instead of TIMESTAMP.
Why it's wrong here
Loses time information entirely.
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 by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.