A company is migrating from a self-managed on-premises Oracle database to Aurora PostgreSQL and needs the cutover to happen with only a few minutes of downtime, even though the full data copy will take many hours. The schema also needs to be converted from Oracle's dialect to PostgreSQL before any data loads. Which combination of AWS services and migration technique fits?
- AWS DMS alone, performing a one-time full load of the data; schema conversion between different database engines is handled automatically by DMS during the full load
- AWS Backup to create a snapshot of the on-premises database, then restore that snapshot directly into a new Aurora PostgreSQL cluster
- AWS DMS Fleet Advisor, which converts the Oracle schema to PostgreSQL and performs the full data load and ongoing replication in a single step
- The AWS Schema Conversion Tool (or DMS Schema Conversion) to convert the Oracle schema to PostgreSQL first, then AWS DMS to perform the full load followed by change data capture (CDC) that replicates ongoing changes until a brief final cutover
Why D? And why not the others?
Correct answer: D. The AWS Schema Conversion Tool (or DMS Schema Conversion) to convert the Oracle schema to PostgreSQL first, then AWS DMS to perform the full load followed by change data capture (CDC) that replicates ongoing changes until a brief final cutover
Converting the schema first with the Schema Conversion Tool (or DMS Schema Conversion) handles the Oracle-to-PostgreSQL dialect differences before any data moves, and then AWS DMS performs the full load and switches into change data capture so that ongoing source changes keep replicating to the target throughout the many-hour copy, letting the team apply the last few minutes of changes and cut over with minimal downtime. The option describing DMS alone with automatic schema conversion is wrong because a plain DMS full load moves data between already-compatible schemas; it does not convert one engine's schema and dialect into another's, and without CDC the source would need to stay frozen for the entire multi-hour copy rather than just a few minutes. The option describing AWS Backup snapshots is wrong because backup snapshots are specific to their source engine's storage format, and a snapshot taken from a self-managed on-premises Oracle database cannot be restored directly into an Aurora PostgreSQL cluster running a different engine. The option describing DMS Fleet Advisor is wrong because Fleet Advisor is a discovery and inventory tool that analyzes on-premises servers to help plan a migration; it does not itself convert schemas, perform full loads, or run CDC replication.
Source: AWS DMS documentation: What is AWS Database Migration Service? (Schema Conversion and CDC replication)