Zero Downtime operations are used to eliminate downtime for upgrades and migrations and fallback strategies. This includes migration of the database from one database technology to another, for example migrating from PostgreSQL to Oracle, or migration of a database into a cloud environment or between cloud vendors, or migration from one operating system to another. The same replication pattern can also be used to eliminate or minimize the outage for upgrades, including application upgrades where the database structure needs to change, or database and operating system upgrades and patches.

Oracle GoldenGate’s adaptability and flexibility allows it to replicate between different databases, database versions, operating systems, and even between tables with different structures. While many zero downtime migrations and upgrades using Oracle GoldenGate can be configured unidirectionally, there are some situations where it is configured bi-directionally. Oracle recommends setting up failback replication stream from the new environment to the old environment to prevent data loss. If there is an issue with the new environment, then the database and Oracle GoldenGate administrators can switch users back to the old environment without any loss of data. This is accomplished by configuring a reverse replication stream from the new environment back to the old database as covered in Bidirectional Replication Using Live Standby Database.

See Best Practices for Logical Database Migration.

Also see Learn About Migrating with Oracle GoldenGate to know more.