As a professional cloud developer with experience across multiple cloud platforms, here are the top 10 AWS Athena interview questions and answers:
- What is Amazon Athena?
Amazon Athena is an interactive query service that enables users to analyze data in Amazon S3 using standard SQL. It is a serverless service, meaning users don’t need to manage any infrastructure and only pay for the queries they run.
- How does Amazon Athena differ from Amazon Redshift?
Amazon Athena is a serverless query service that analyzes data directly in S3, while Amazon Redshift is a fully-managed, petabyte-scale data warehouse service. Athena is designed for ad-hoc querying of data, whereas Redshift is more suited for complex analysis and aggregation tasks.
- What file formats does Amazon Athena support?
Athena supports several file formats, including CSV, JSON, Parquet, ORC, Avro, and more. It also supports compressed data formats such as Gzip, Snappy, LZO, and Bzip2.
- How does Amazon Athena handle schema-on-read?
Athena uses schema-on-read, meaning it applies a schema to the data when a query is executed. This allows users to define the schema for the data in the AWS Glue Data Catalog or through a CREATE TABLE statement at runtime.
- Can you explain partitions in Amazon Athena?
Partitions are a way to organize your data in Amazon S3, which can improve query performance by reducing the amount of data scanned. When you create a table in Athena, you can specify partition keys that are used to divide the data into smaller, more manageable pieces.
- How is data in Amazon Athena secured?
Athena uses AWS Identity and Access Management (IAM) to control access to its resources. Users can define IAM policies to restrict access to specific databases, tables, or actions. Additionally, data can be encrypted at rest in S3 and in transit using SSL/TLS.
- How are Amazon Athena queries priced?
Athena queries are priced based on the amount of data scanned. Users pay a fixed rate per TB of data scanned, with a minimum of 10 MB per query. Queries that return no results are not billed.
- Can you explain the concept of Amazon Athena workgroups?
Workgroups are a way to isolate query execution and control costs in Athena. Users can create separate workgroups for different teams or projects and define resource limits, such as the total amount of data scanned per day, to control costs.
- How do you optimize Amazon Athena query performance?
Some ways to optimize Athena query performance include:
- Partitioning your data to reduce the amount of data scanned.
- Converting data to columnar formats like Parquet or ORC.
- Using compression to reduce the amount of data read.
- Using LIMIT clauses to limit the number of rows returned.
Utilizing CTAS (Create Table As Select) to cache intermediate results.
How can you view the query history and performance metrics in Amazon Athena?
You can view the query history in the Athena console, which includes information such as query duration, data scanned, and query status. For more detailed performance metrics, you can enable Amazon CloudWatch integration to monitor query performance, errors, and resource utilization.
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