The answer is that the partitions have not been added to the Glue Data Catalog. This is the most likely cause because the AWS CLI command shown only retrieves table metadata, not partition metadata, and without registered partitions, Athena cannot locate the data files stored under partitioned S3 paths like `s3://bucket/year=2024/month=01/`. Even though the table schema is defined, Athena returns no data when it cannot map those S3 prefixes to the query engine. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding of the Glue Data Catalog’s partition registration requirement—a common trap is assuming that simply defining a table with a partitioned schema is enough. Remember, Athena relies on explicit partition metadata, which must be added via `MSCK REPAIR TABLE`, `ALTER TABLE ADD PARTITION`, or a Glue crawler. Memory tip: think “No partitions, no data—Athena needs a map to the S3 paths.”
DEA-C01 Data Store Management Practice Question
This DEA-C01 practice question tests your understanding of data store management. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Network Topology
Refer to the exhibit. A data engineer runs the above AWS CLI command to view the table metadata in the AWS Glue Data Catalog. The data is stored as CSV in S3 with partitions by year and month. When querying the table using Amazon Athena, no data is returned. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The partitions have not been added to the Glue Data Catalog.
Option A is correct because the AWS CLI command shown only retrieves table metadata, not partition metadata. In AWS Glue, partitions must be explicitly added to the Data Catalog via `MSCK REPAIR TABLE`, `ALTER TABLE ADD PARTITION`, or a Glue crawler. Without partition metadata, Athena cannot locate the data files under the partitioned S3 paths (e.g., `s3://bucket/year=2024/month=01/`), resulting in zero rows returned even though the table schema is defined.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
The partitions have not been added to the Glue Data Catalog.
Why this is correct
Partitions must be explicitly registered for Athena to query them.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The SerDe is not compatible with CSV files.
Why it's wrong here
OpenCSVSerde is designed for CSV files.
✗
The S3 location points to a file instead of a folder.
Why it's wrong here
The location is a prefix ending with /, indicating a folder.
✗
The column data types are incorrect for the CSV data.
Why it's wrong here
The types int, double, string are suitable for typical CSV data.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume the `PARTITIONED BY` clause in the table definition automatically registers the partitions in the Glue Data Catalog, but it only defines the schema; partition metadata must be added separately.
Detailed technical explanation
How to think about this question
Under the hood, Glue Data Catalog stores table metadata separately from partition metadata. When partitions are not registered, Athena's query engine has no knowledge of the subdirectories under the table location, so it scans only the base path (which contains no data files). A common real-world scenario is after a one-time bulk load of partitioned data into S3; running `MSCK REPAIR TABLE` is essential to sync the partition metadata. The `PARTITIONED BY` clause in the DDL defines the partition keys, but the actual partition values must be added to the catalog for Athena to discover them.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Data Store Management — This question tests Data Store Management — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The partitions have not been added to the Glue Data Catalog. — Option A is correct because the AWS CLI command shown only retrieves table metadata, not partition metadata. In AWS Glue, partitions must be explicitly added to the Data Catalog via `MSCK REPAIR TABLE`, `ALTER TABLE ADD PARTITION`, or a Glue crawler. Without partition metadata, Athena cannot locate the data files under the partitioned S3 paths (e.g., `s3://bucket/year=2024/month=01/`), resulting in zero rows returned even though the table schema is defined.
What should I do if I get this DEA-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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