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S3 Select

5 minutes 5 Questions

S3 Select is a feature that enables querying and filtering individual objects in Amazon S3 without the need to retrieve the entire object first. It supports SQL-like expressions for selecting data from CSV, JSON, or Apache Parquet files, and can directly integrate with other AWS services like Amazo…

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AWS Certified Solutions Architect - S3 Select Example Questions

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Question 1

An application reads large individual CSV objects stored in Amazon S3. To minimize data transfer and processing cost, it must retrieve only specific columns and only rows that match simple filter predicates from within each single object. The team does not want to create external tables or run a separate query engine; they want to fetch just the matching records directly from S3 during the read. Which AWS service or feature should they use?

Correct Answer: S3 Select

S3 Select allows an application to use simple SQL expressions to retrieve only the required rows and columns from within a single object stored in Amazon S3 (CSV, JSON, or Parquet), reducing data transferred and processing cost. It does not require creating external tables or running a query engine. Athena is better for ad hoc analytics across many objects and uses a serverless query engine; Glue is for ETL orchestration and data cataloging; EMR provisions clusters for big data processing. For per-object, in-place filtering directly from S3 during reads, S3 Select is the correct choice.

Question 2

An application uploads files to Amazon S3, and a downstream process reads those files. To reduce the processing time, you need to filter out unnecessary data. Which S3 feature will save cost and reduce processing time?

Correct Answer: S3 Select

S3 Select allows applications to retrieve only a subset of data from an object by using simple SQL expressions. This feature can save cost and reduce the processing time by filtering unnecessary data. Other options like S3 Inventory, Transfer Acceleration, Lifecycle Policies, Cross-Region Replication, and Object Lock are not directly related to filtering data.

Question 3

An organization deals with large CSV files containing customer data stored in Amazon S3. They want to perform selective queries to identify customers based on specific criteria. Which AWS service would be most appropriate to accomplish this task?

Correct Answer: Amazon Athena

Amazon Athena is the most appropriate AWS service for performing selective queries on large CSV files stored in Amazon S3. Athena is a serverless, interactive query service that allows users to analyze data directly in S3 using standard SQL. It is designed to work with various data formats, including CSV, and can efficiently process large datasets. Athena eliminates the need for complex ETL processes or data warehousing, making it ideal for ad-hoc queries and analysis of data stored in S3. It can easily handle selective queries based on specific criteria, allowing organizations to quickly identify customers that meet certain conditions. Athena's serverless nature means there's no infrastructure to manage, and users only pay for the queries they run, making it a cost-effective solution for this use case.

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