The answer is an INPUTFORMAT mismatch, specifically using TextInputFormat instead of the required MapredParquetInputFormat for Parquet tables. When you run an Athena DDL statement that defines a table with a Parquet SerDe but pairs it with an incompatible INPUTFORMAT like TextInputFormat, Athena cannot correctly interpret the underlying file structure, causing a query error. This scenario tests your understanding of how Athena relies on the exact combination of SerDe and INPUTFORMAT to read data; for Parquet files, the correct INPUTFORMAT is 'org.apache.hadoop.hive.ql.io.parquet.MapredParquetInputFormat'. On the AWS Certified Data Engineer Associate DEA-C01 exam, this is a common trap where candidates focus on the SerDe being correct but overlook the INPUTFORMAT, which must match the file format. A reliable memory tip is to remember that Parquet always pairs with MapredParquetInputFormat, just as ORC pairs with OrcInputFormat—never mix a columnar format with a text-based input format.
DEA-C01 Data Store Management Practice Question
This DEA-C01 practice question tests your understanding of data store management. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Exhibit
Refer to the exhibit.
CREATE EXTERNAL TABLE my_table (
id INT,
name STRING,
value DOUBLE
)
ROW FORMAT SERDE 'org.apache.hadoop.hive.ql.io.parquet.serde.ParquetHiveSerDe'
STORED AS INPUTFORMAT 'org.apache.hadoop.mapred.TextInputFormat'
OUTPUTFORMAT 'org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat'
LOCATION 's3://my-bucket/data/'
TBLPROPERTIES ('classification'='parquet');
A data engineer runs the above DDL statement in Amazon Athena. The query returns an error. 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.
Refer to the exhibit.
CREATE EXTERNAL TABLE my_table (
id INT,
name STRING,
value DOUBLE
)
ROW FORMAT SERDE 'org.apache.hadoop.hive.ql.io.parquet.serde.ParquetHiveSerDe'
STORED AS INPUTFORMAT 'org.apache.hadoop.mapred.TextInputFormat'
OUTPUTFORMAT 'org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat'
LOCATION 's3://my-bucket/data/'
TBLPROPERTIES ('classification'='parquet');
A
The SerDe is not compatible with Parquet files.
Why wrong: ParquetHiveSerDe is correct for Parquet.
B
The INPUTFORMAT is incorrect for Parquet files.
TextInputFormat is for text files, not Parquet. Should use Parquet input format.
C
The S3 bucket location does not exist.
Why wrong: The error is due to incompatible format, not missing location.
D
The table name contains underscores.
Why wrong: Underscores are allowed in Athena table names.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The INPUTFORMAT is incorrect for Parquet files.
Option D is correct because the table is defined with Parquet SerDe but the INPUTFORMAT is TextInputFormat, which is incompatible. For Parquet files, the INPUTFORMAT should be 'org.apache.hadoop.hive.ql.io.parquet.MapredParquetInputFormat'. Option A is wrong because the location is valid. Option B is wrong because the table name is valid. Option C is wrong because the SerDe is correct for Parquet, but the mismatch with INPUTFORMAT causes the error.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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 SerDe is not compatible with Parquet files.
Why it's wrong here
ParquetHiveSerDe is correct for Parquet.
✓
The INPUTFORMAT is incorrect for Parquet files.
Why this is correct
TextInputFormat is for text files, not Parquet. Should use Parquet input format.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
✗
The S3 bucket location does not exist.
Why it's wrong here
The error is due to incompatible format, not missing location.
✗
The table name contains underscores.
Why it's wrong here
Underscores are allowed in Athena table names.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related DEA-C01 NAT questions on configuration and troubleshooting.
Data Store Management — This question tests Data Store Management — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The INPUTFORMAT is incorrect for Parquet files. — Option D is correct because the table is defined with Parquet SerDe but the INPUTFORMAT is TextInputFormat, which is incompatible. For Parquet files, the INPUTFORMAT should be 'org.apache.hadoop.hive.ql.io.parquet.MapredParquetInputFormat'. Option A is wrong because the location is valid. Option B is wrong because the table name is valid. Option C is wrong because the SerDe is correct for Parquet, but the mismatch with INPUTFORMAT causes the error.
What should I do if I get this DEA-C01 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related DEA-C01 NAT questions on configuration and troubleshooting.
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?
Static NAT maps one inside address to one outside address.
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