Migrating and Modernizing Oracle Databases to PostgreSQL on AWS – Part 3: Planning and Execution

This article outlines planning and execution strategies for migrating Oracle databases to PostgreSQL on AWS, using a fictional insurance company managing 42 databases as a case study.

• Design cloud-native target architectures by decoupling services, optimizing schemas, and selecting between Amazon Aurora and RDS for PostgreSQL based on workload requirements
• Execute application remediation across 100+ applications, updating drivers, SQL syntax, and stored procedures while implementing PgBouncer for connection pooling
• Replace Oracle-specific features with AWS services: Oracle AQ with SNS/SQS, DBMS_SCHEDULER with EventBridge/Lambda, UTL_FILE with S3, and database links with API Gateway
• Implement four-wave migration strategy progressing from low-risk systems to mission-critical workloads over 36 weeks with structured validation
• Establish multi-dimensional testing framework validating structural integrity, quantitative accuracy of 2.8 billion rows, 15,000 test cases, and operational performance
• Deploy tiered rollback strategies: blue-green for mission-critical systems, replication-based for moderate criticality, DNS fallback for low-risk workloads

Strategic modernization combined with phased risk mitigation enables organizations to transition from Oracle to PostgreSQL while maintaining business continuity and achieving cloud-native agility.