S3 Select vs Athena for Parquet Column Query

DEA-C01 By islever Editorial Last updated Oct 12, 2026

Perform data ingestion.

Short answer

B Use S3 Select to write a SQL SELECT statement to retrieve the required column from the S3 objects.

Question

A data engineer has a one-time task to read data from objects that are in Apache Parquet format in an Amazon S3 bucket. The data engineer needs to query only one column of the data. Which solution will meet these requirements with the LEAST operational overhead?

Configure an AWS Lambda function to load data from the S3 bucket into a pandas dataframe. Write a SQL SELECT statement on the dataframe to query the required column.
Use S3 Select to write a SQL SELECT statement to retrieve the required column from the S3 objects. Correct Answer
Prepare an AWS Glue DataBrew project to consume the S3 objects and to query the required column.
Run an AWS Glue crawler on the S3 objects. Use a SQL SELECT statement in Amazon Athena to query the required column.

Key Takeaways

The core concept is efficient data retrieval using S3 Select, and the common trap is assuming it only works on CSV/JSON or cannot handle Parquet formats.

This question evaluates the optimal AWS service for querying a single column from Apache Parquet files in S3 with minimal overhead. The correct solution leverages S3 Select's native filtering capabilities to avoid scanning entire objects.

Common mistake: Many learners choose D (Athena) because they believe S3 Select is limited to single files or deprecated, overlooking its support for columnar formats like Parquet and its lower operational overhead.

Expert Analysis

Why the Answer Is Correct

B is the correct answer because Amazon S3 Select allows you to retrieve subsets of data from an object using SQL expressions. It supports both CSV and Apache Parquet formats, enabling column-level filtering directly at the storage layer. This avoids downloading full objects, which significantly reduces operational overhead compared to other methods.

Why the Other Options Are Wrong

Option A involves Lambda and pandas, which requires writing code and managing compute resources, increasing overhead. Option C, AWS Glue DataBrew, is a visual data preparation tool, not optimized for one-time programmatic queries. Option D uses Athena, which scans full partitions; while effective, it has higher latency and cost than S3 Select for simple column extractions from small datasets.

Community Comment Notes

Several commenters argue that S3 Select is discontinued or limited to single objects. As user JoeAWSOCM noted, "S3 select is for querying one object," but this is incorrect as S3 Select can be used programmatically to query multiple objects via batch operations or scripts, though typically it targets specific keys. However, the consensus in the exam context emphasizes S3 Select's efficiency for such tasks despite community skepticism about its scope.

Official Reference

https://docs.aws.amazon.com/AmazonS3/latest/userguide/using-s3-select.html

This link opens the official vendor documentation in a new tab.

Exam Strategy

When asked for 'least operational overhead' for reading specific data from S3, consider S3 Select before launching full services like Athena or EMR. Always verify if the format (like Parquet) is supported by the lighter-weight tool.

Frequently Asked Questions

Does S3 Select support Apache Parquet?

Yes, S3 Select supports both CSV and Apache Parquet formats, allowing efficient column-level filtering.

Is S3 Select discontinued?

No, it is not discontinued. While availability may vary by region or account type, it remains a valid feature for querying objects.

More DEA-C01 FAQ →

Community Votes

71%

29%

71% of anonymous learners picked answer B. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 8 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 8

JoeAWSOCM 👍 4 Answered D

S3 select is for querying one object. Here the requirement is to query one column from multiple objects. Also S3 select is discontinued for new users. So answer could be D
rralucard_ 👍 3 Answered B

https://docs.aws.amazon.com/AmazonS3/latest/userguide/storage-inventory-athena-query.html S3 Select allows you to retrieve a subset of data from an object stored in S3 using simple SQL expressions. It is capable of working directly with objects in Parquet format.
dungct 👍 3

but s3 select can only select one object
GiorgioGss 👍 2 Answered B

https://docs.aws.amazon.com/AmazonS3/latest/userguide/using-select.html
catoteja 👍 1

Amazon S3 Select is no longer available to new customers. Existing customers of Amazon S3 Select can continue to use the feature as usual But with it you can only query one object xD. Glue + athena

Show 3 more comments

FunkyFresco 👍 2 Answered B

if is one-time task
hogs 👍 2 Answered B

omly once
imymoco 👍 1 Answered B

only one column -> S3 select

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