About Refreshable Clones on Autonomous Database

When you create a refreshable clone for an Autonomous Database instance the system clones the source database to the refreshable clone. After you create a refreshable clone you can refresh the clone with changes from the source database.

Refreshable Clone Features

A refreshable clone allows you to do the following:

  • Maintain one or more copies of the source database for use as read-only databases. A clone database is available when you need it, and when you want to update the data, you can refresh the clone from the source database.

  • Share copies of a production database with multiple business units. For example, one business unit might use the source database for ongoing transactions and another business unit could at the same time use the refreshable clone database for read-only operations.

    This option also allows you to spread the cost of database usage across multiple business units. You can bill the different units separately, based on their usage of one or more refreshable clone databases.

Note:

Refreshable clones have a one week refresh age limit. If you do not perform a refresh within a week, then the refreshable clone is no longer refreshable. After a refreshable clone passes the refresh time limit, you can use the instance as a read only database or you can disconnect from the source to make the database a read/write (standard) database.

Refreshable Clone Operations

You can create a refreshable clone from an Autonomous Database instance. After you create a refreshable clone you can perform several operations on the refreshable clone, including: refresh, stop, start, restart, disconnect from source, and terminate.

Operation Description
Create

You can create a refreshable clone from an Autonomous Database instance. You can create more than one refreshable clone using the same Autonomous Database instance as a source.

See Create a Refreshable Clone for an Autonomous Database Instance for the steps to create a refreshable clone.

View

You view a refreshable clone from the Oracle Cloud Infrastructure console Autonomous Database Details page.

See View Refreshable Clones for an Autonomous Database Instance for more information.

Start or Restart

When a refreshable clone is stopped as indicated by the Lifecycle State Stopped, you can start the database.

When a refreshable clone is available as indicated by the Lifecycle State Available, you can restart the database.

Refresh

For a refreshable clone, you can refresh the clone with data from the source database. See Refresh a Refreshable Clone on Autonomous Database for more information.

Disconnect Clone from Source

You can disconnect a refreshable clone from the source database to make the clone a standard read/write database. Disconnecting a refreshable clone disassociates the clone database from the source database.

See Disconnect a Refreshable Clone from the Source Database for more information.

Stop

When a refreshable clone is stopped, database operations are not available and charging for OCPU usage on the refreshable clone stops.

Terminate

If you want to terminate a refreshable clone, select More Actions and Terminate. Terminating a refreshable clone disassociates the clone database from the source database.

Refreshable Clone Lifecycle States

After you create a refreshable clone, the clone indicates its state on the Autonomous Database Information page in the Lifecycle State field. In addition, the Mode field indicates that a refreshable clone is Read-Only.

A refreshable clone indicates its state as follows:

  • Updating: When a refreshable clone is refreshing, the Lifecycle State field shows Updating. While the database is refreshing connections and queries wait until the refresh completes. After the refresh completes the state is set to Available, and connections and queries resume.

    See Refresh a Refreshable Clone on Autonomous Database for more information.

  • Stopped: When a refreshable clone is stopped, database operations are not available and charging for OCPU usage on the refreshable clone stops.

  • Available: When the refreshable clone is available, database operations are available and you are charged for OCPU usage on the refreshable clone.

The Autonomous Database Information page Mode field indicates the database mode, as follows:

  • Read-Only: No data can be inserted into or updated in a refreshable clone as it is a read-only database. You can use a refreshable clone for read-only queries and for reporting.

    See Disconnect a Refreshable Clone from the Source Database to change the database to Read/Write mode. In this case the refreshable clone is disconnected from the source database.

Refreshable Clone Refresh Timing and Disconnecting from the Source Database

A banner on the Oracle Cloud Infrastructure console displays the date and time up to which you can refresh the refreshable clone. The banner also includes a Refresh Clone button.

Description of adb_refreshable_clone_refresh_clone.png follows
Description of the illustration adb_refreshable_clone_refresh_clone.png

When a refreshable clone is not refreshed within seven (7) days from the last refresh, the banner messages changes to indicate that a refreshable clone that has not been refreshed within seven days cannot be refreshed. The button in the banner changes to Disconnect Clone from Source Database.

When a refreshable clone has not been refreshed within seven days and the refreshable clone has exceeded its maximum refresh time, you have the following options:

  • You can continue to use the refreshable clone as a read-only database. The refreshable clone is not refreshable and the data on the refreshable clone reflects the state of the source database at the time of the last successful refresh.

  • You can disconnect the refreshable clone from the source database. This disconnects the refreshable clone from the source Autonomous Database instance. This is a one time operation, is irreversible, and converts the database from a refreshable clone to a regular database in Read/Write mode.

    See Disconnect a Refreshable Clone from the Source Database for more information.

When a refreshable clone has exceeded the maximum refresh time, if you want to use a refreshable clone that can be refreshed from the source database, then you must create a new refreshable clone. If you create a new refreshable clone, then you might also want to terminate the refreshable clone that is no longer able to refresh from the source database.

Operations on an Autonomous Database with an Attached Refreshable Clone

Describes details for using a source Autonomous Database instance that has one or more attached refreshable clones.

When you make certain changes on a source Autonomous Database instance that has one or more refreshable clones attached to it, the changes are applied to both the source database and to the refreshable clones as follows:

  • Storage: The storage value you set on the source database applies to both the source database and to any attached refreshable clones.

  • ADMIN password: The ADMIN password value you set on the source database applies to both the source database and to any attached refreshable clones.

To view the refreshable clones for a source database, on the Autonomous Database Details page, under Resources, click Refreshable Clones. The Autonomous Database resources area provides a link to each refreshable clone in the Display Name field, and includes the Last Refresh timestamp field and the Refresh Point timestamp field. The refresh point specifies the timestamp for the source database data to which the refreshable clone data is refreshed.

If you want to terminate a source database that has one or more attached refreshable clones, then before you terminate the source database you must do the following until there are no longer any attached refreshable clones. For each attached refreshable clone, do one of the following:

  • Disconnect the refreshable clone from the source database. See Disconnect a Refreshable Clone from the Source Database for more information.
  • Terminate the refreshable clone to disassociate the refreshable clone from the source database. You can terminate a refreshable clone by selecting More Actions and Terminate.

Refreshable Clone Notes

Lists limitations and notes for Autonomous Database refreshable clones.

  • Always Free Autonomous Databases do not support refreshable clones.

  • You cannot create a cascading series of refreshable clones. Thus, a refreshable clone cannot be created from another refreshable clone.

  • You cannot backup or restore a refreshable clone.

  • The ADMIN password for a refreshable clone is inherited from the source database. If you want to change the ADMIN password for a refreshable clone you must change the ADMIN password on the source database, and then refresh the clone for the ADMIN password on the clone to come into effect.

  • Oracle Application Express (APEX) URLs do not work in a refreshable clone read-only database and the APEX URLs are disabled in the Oracle Cloud Infrastructure console and the Autonomous Database Service Console. APEX URLs are enabled for a read/write database when a refreshable clone is disconnected from the source.

  • Oracle Machine Learning is disabled in a refreshable clone read-only database. In addition, the OML User Administration URLs are disabled in the Oracle Cloud Infrastructure console and in the Autonomous Database Service Console.

  • Oracle Data Safe is not supported for a refreshable clone instance. The Data Safe data in the refreshable clone's source database, for example user registration, data masking, and so on are available and Data Safe can be enabled when a refreshable clone is disconnected from the source.

  • When you scale up or scale down the storage on the source Autonomous Database instance for a refreshable clone, the change is immediately reflected in the database console and in the billing for the refreshable clone. When the refreshable clone is refreshed to a refresh point after the scale up or down operation, the system makes a corresponding change to the refreshable clone storage (scaling up or scaling down the refreshable clone storage to match the source database).

  • You cannot use the rename operation on a refreshable clone instance or on a database that is the source for a refreshable clone.

  • Automatic Workload Repository (AWR) data and reports are not available for refreshable clones. In addition, the graphs that rely on AWR data are not available, including the following graphs:

    • The Running SQL Statements graph on the Overview page of the service console.

    • The SQL Response Time graph on the Overview page of the service console.

    • The Time Period graphs on the Activity page of the Service Console.

    • Performance Hub graph data older than one hour is not available.