Domain 4.3: Design migrations — AZ-305 Practice Question 48

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Identify the need for schema conversion (heterogeneous migration) and continuous data sync (Online migration for near-zero downtime).

Full Answer

Azure Database Migration Service (DMS) configured for Online migration, and SQL Server Migration Assistant (SSMA) for Oracle (or Ora2Pg) for schema conversion.

Migrating from Oracle to PostgreSQL is a heterogeneous migration. First, you must convert the schema (tables, views, stored procedures) using a tool like SSMA for Oracle or Ora2Pg. Second, to meet the 15-minute downtime requirement for a 5 TB database, you must use Azure Database Migration Service (DMS) in 'Online' mode. Online mode performs an initial load and then continuously replicates changes (CDC) from Oracle to PostgreSQL. When you are ready, you stop the application, let the final few transactions sync, and cut over to Azure within minutes.

Common mistakes

Selecting Offline migration. Copying 5 TB over a network offline will take hours or days, causing massive downtime.

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Common mistakes

Practice the full Azure Solutions Architect Expert AZ-305 Practice Exam 1

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