Database Modernization And Migration Strategy — AWS Solutions Architect (SAA-C03)
Heterogeneous migration requires schema conversion before replication
Architecture requirement: migrate an on-premises Oracle or SQL Server database to Aurora PostgreSQL with minimal application disruption. Competing choices: DMS alone, SCT then DMS, native export/import, or Snowball for large initial datasets. Deciding constraint: are source and target engines compatible? DMS replicates data; SCT converts schema and stored procedures for heterogeneous migrations. Using DMS without SCT on a heterogeneous pair leaves unconverted schema objects that break the target. Both tools are required when engine types differ.
What This Pattern Tests
The exam tests database migration approach selection. Homogeneous migration (Oracle to Oracle on RDS, PostgreSQL to Aurora PostgreSQL) uses DMS with direct replication — minimal schema changes. Heterogeneous migration (Oracle to Aurora PostgreSQL, SQL Server to MySQL) requires AWS Schema Conversion Tool (SCT) to convert schema and stored procedures first, then DMS for data. Modernization to DynamoDB or DocumentDB requires application-level changes because the data model changes fundamentally. The trap is assuming DMS handles schema conversion (it migrates data, not schema) or that NoSQL migration is just a data copy (the application queries must change).
Decision Axis
Schema compatibility determines approach: same engine = DMS, different engine = SCT + DMS, different model (relational to NoSQL) = application rewrite.
Associated Traps
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Decision Rules
Determine whether the stated read-replica count and failover-speed requirements exceed the RDS Multi-AZ ceilings, mandating Amazon Aurora over Amazon RDS Multi-AZ.
Choose Aurora Serverless v2 Multi-AZ over provisioned Aurora Multi-AZ when the workload exhibits large idle-to-peak swings and the dominant constraint is minimising monthly database cost without relaxing an availability SLA.
Domain Coverage
Difficulty Breakdown