Lowering AWS KMS decrypt API costs in EMR Spark jobs

This article presents practical techniques to reduce AWS KMS decrypt API costs when processing encrypted data with Amazon EMR and Apache Spark.

• Data aggregation consolidates small S3 files into larger blocks to reduce redundant decrypt calls
• Columnar formats like Parquet and ORC enable reading only required columns, improving I/O efficiency
• Apache Iceberg provides automatic file layout optimization and partition handling for data lakes
• Compression reduces data size and accelerates reads between S3 and Spark
• AWS Glue Data Catalog partition indexes enable server-side filtering to reduce S3 object scans
• These techniques can be used independently or together when S3 Bucket Keys cannot meet auditability requirements

Organizations can significantly lower operational costs by implementing these optimization strategies while maintaining encryption and compliance standards.