Keeping test and development environments current shouldn’t drain time or resources. Yet for many Database Administrators (DBAs), cloning and refreshing databases using traditional tools like RMAN and Data Pump can be slow, manual, and disruptive to production systems.
Oracle’s Autonomous Database (ADB) introduces a smarter solution: automatically refreshable clones. This feature gives development teams access to up-to-date data on a set schedule, without affecting the source environment. The result is faster testing, reduced risk, and greater confidence in the accuracy of your data.
These clones operate independently, ensuring that testing and development are conducted on the latest and most relevant data sets without impacting the source environment.
Implementation
Implementing refreshable clones in Oracle’s Autonomous Database is a straightforward process. It begins by creating a clone from the source database—without disrupting the live environment.
Once created, the clone runs independently with its own compute and storage resources. This separation ensures there’s no performance impact on production systems, allowing teams to move faster without added risk.
Types of Cloning in Oracle Autonomous Database
Full Clone: This creates a new database with the source database’s data & metadata.
Refreshable Clone: This creates a read-only copy of the source database’s data and metadata. You can refresh this with the source database’s data periodically.
Metadata Clone: This creates a new database with only the metadata of source database.
Schedules
You can schedule refreshes at regular intervals based on your business requirements.
Incremental Refresh Mechanism
One of the key advantages of refreshable clones is their incremental refresh capability. Instead of replicating the entire database, only the changes made since the last update are applied to the clone. This significantly reduces data transfer, shortens refresh times, and minimizes the strain on network and system resources.
Critical Features of Refreshable Clone
Maintain one or multiple copies of the source database for use as read-only databases.
- Create one or more clones in regions outside of your source database’s primary region. These remote region clones can be refreshed from the source.
- Share copies of a production database with multiple business units.
- Use a refreshable clone as a test database. You can test out DML operations, calculations, and other tests as needed while staying disconnected from the source database. When you’re done with testing, you can reconnect to the source and refresh the clone.
Refreshable Clone Operations
- Create: Creates a refreshable clone from an Autonomous Database instance. You can create multiple refreshable clones from the same Autonomous Database instance.
- Start or Restart: When a refreshable clone has a status of Lifecycle State Stopped, you can start the database with this operation.
- Stop: This stops the refreshable clone, making database operations unavailable and charging for OCPU usage on these stops.
- Terminate: This terminates a refreshable clone.
- Disconnect Clone from Source: Turn a refreshable clone into a standard read/write database with this command.
- Refresh: Refresh a refreshable clone. These clones have a one-week refresh age limit. If you do not perform a refresh operation within a week, then this clone is not able to be refreshed.
Automatic Refresh
By default, you can manually refresh a refreshable clone with changes from the source database. However, when automatic refresh is enabled, ADB will automatically refresh a refreshable clone with data from the source database at given time intervals. This refreshing process still adheres to the one-week refresh age limit, however.
Limitations of ADB Refreshable Clones
- The refreshable clone feature is not available in the Always Free Autonomous Database. You need Oracle Database 19c and onwards in Oracle Cloud Infrastructure (OCI) to access it.
- You can’t create a refreshable clone from another refreshable clone.
- You can’t backup or restore a refreshable clone.
- You can’t rename a refreshable clone or a database that is the source for a refreshable clone.
- Creating a cross-region refreshable clone with an Oracle Database 19c source and an Oracle Database 23ai refreshable clone isn’t supported.
- Creating a cross tenancy refreshable clone with an Oracle Database 19c source and an Oracle Database 23ai refreshable clone isn’t supported in either the same region or cross-region.
- The ADMIN password for a refreshable clone is inherited from the source database. You have to change the ADMIN password for the source database, then refresh the clone, to be able to update this information.
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