Describes 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.

• Create one or more clones in regions other than the region of your primary (source) database. Clones in remote regions can be refreshed from the source database.

• You can enable the refreshable clone automatic refresh option. With automatic refresh enabled Autonomous Database automatically refreshes the clone with data from the source. See Refreshable Clone with Automatic Refresh Enabled for more information.

• 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.

• Use a refreshable clone as a test database. You can disconnect a refreshable clone from its source and perform DML operations or calculations as needed, in addition to querying data. This allows you to run DML and make changes while the database is disconnected. When you are done with your testing you can reconnect to the source database, which refreshes the clone to the point where it was when you disconnected.

  The reconnect operation is only available for 24 hours after the disconnect time. If you do not reconnect within the reconnect period, the clone is disconnected from the source database and refreshing and reconnecting are not possible.

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.

By default you manually refresh a refreshable clone with changes from the source database. When you enable the automatic refresh option, Autonomous Database automatically refreshes a refreshable clone with data from the source database at given time intervals.

Note the following for a refreshable clone with automatic refresh enabled:

• You can manually refresh a refreshable clone between automatic refreshes. If you manually refresh to a refresh point later than the next refresh point specified for an automatic refresh, the automatic refresh may fail. Following refreshes, after the failed refresh, are attempted at the next scheduled automatic refresh.

• If a refreshable clone is stopped, disconnected, or already at a later timestamp than the specified automatic refresh point, the automatic refresh fails.

• If a scheduled refresh is missed due to the source database being stopped, or the refreshable clone being disconnected, or when the refreshable clone was manually refreshed to later point, the missed refresh is skipped. The refreshable clone refreshes at the next scheduled interval.

• When an automatic refresh is missed, Autonomous Database does the following:

  • Shows a banner on the Oracle Cloud Infrastructure Console.

    For example:

    
    

  • Generates the automatic refresh failed event. See Autonomous Database Event Types for more information.

• If no refresh is performed within 7 days, the refreshable clone can no longer be refreshed.

  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.

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

• You can subscribe to the Information event com.oraclecloud.databaseservice.autonomous.database.information to be notified about the completion or failure of a scheduled Automatic Refresh. See Information Events on Autonomous Database for more information.

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 or reconnecting, 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.

A refreshable clone with Automatic refresh disabled has a one week refresh age limit and 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.

When a refreshable clone that has Auto refresh disabled is not refreshed within seven (7) days from the last refresh, the banner message changes to indicate that the 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.

  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, you must create a new refreshable clone. If you create a new refreshable clone, you might also want to terminate the refreshable clone that is no longer able to refresh from the source database.

After you perform a Disconnect refreshable clone operation, a banner displays the date and time up to which you can reconnect the database to the source. The banner also includes a Reconnect refreshable clone button.

When a disconnected database is not reconnected within 24 hours from the disconnect time, the Oracle Cloud Infrastructure Console removes the reconnect refreshable clone banner.

When a disconnected refreshable clone has exceeded the reconnect period, you have the following options:

• You can use the database as a standard Autonomous Database; there is no longer an option to reconnect the database to the source database.

• 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 want to terminate the disconnected clone that is no longer able to refresh from the source database.

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.