DEA-C01 practice question: File formats and conversion (1 of 2)
Data Ingestion and Transformation A free question from our original DEA-C01 practice exam. Try it, then open the answer to see why each option is right or wrong.
An esports league sends player-telemetry events as JSON records through Amazon Data Firehose into Amazon S3. Analysts query the data with Amazon Athena, and the team wants the files delivered as Parquet, not JSON.
The team does not want to run an extra conversion job after delivery, and it wants the change to stay within the existing delivery stream.
Which change meets these requirements?
Choose one answer.
AA. Turn on gzip compression for the delivery stream, so that the JSON files in S3 are smaller and cheaper to scan.
BB. Add an AWS Lambda transformation to the delivery stream that writes each record as a separate Parquet file in S3.
CC. Create a Glue Data Catalog table for the event schema, and turn on Parquet record format conversion in the delivery stream.
DD. Set a larger buffer size on the delivery stream, and run an Athena CTAS query after each delivery to write Parquet copies.
Show the answer and explanation
Answer: C
A. Wrong: Gzip compresses the JSON but keeps the row-based JSON format. The team asked for Parquet, so this option does not meet the requirement.
B. Wrong: A Lambda transformation could produce Parquet, but writing one file per record creates a huge number of small objects. The option is also more custom code than the team wants.
C. Right: Correct. Firehose converts JSON to Parquet or ORC using the schema in a Glue Data Catalog table, and it converts each record before writing to S3. No separate job runs after delivery, and the existing stream stays in place. Learn more: Enable record format conversion (opens in a new tab)
D. Wrong: A larger buffer does not change the format, and the CTAS query is the extra job the team does not want to run. The option misses both the format and the no-extra-job requirements.
Explanation
Firehose can convert records to Parquet or ORC during delivery, which avoids a separate job. It needs a Glue Data Catalog table that describes the schema, and it applies that schema to each record before writing to S3. Compression, a larger buffer, or a per-record function do not change the format in the same way.
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