When you create a refreshable clone for an Autonomous Database instance
the system clones the source database to a database that can be refreshed
from the source.
Refreshable clones are billed based on their base CPU count, plus any
additional CPU usage if compute auto scaling is enabled; they do not get billed additionally for the
CPUs of the source database. The number of base CPUs is specified by the
number of ECPUs (OCPUs if your database uses
OCPUs) as shown in the ECPU count or
OCPU count field on the Oracle Cloud
Infrastructure Console. See Oracle Autonomous Database Serverless Features Billing for more information.
Using Cloud Links you can specify that access to a data set from one
or more databases is offloaded to a refreshable clone. When a consumer Autonomous Database is listed
in a data set's offload list, access to the data set is directed to the
refreshable clone. See Register a Data Set with Offload Targets for Data Set Access for more information.
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.
Refreshable Clone with Automatic Refresh Enabled 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.
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.
Refreshable Clone Refresh Timing and Disconnecting 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.
Refreshable Clone Reconnect to 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.
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.
Note
Refreshable clones have a one week
refresh age limit. If you do not perform a refresh within a week, 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.
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.
When you enable the automatic refresh option a
refreshable clone automatically refreshes from the source database
at regular intervals. By default, automatic refresh is disabled and
you must manually refresh at least once every 7 days. See Edit Automatic Refresh Policy for Refreshable Clone 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.
When a clone database is disconnected, you can use the
clone as a standard read/write database. There is a 24 hour
reconnect period where you can reconnect the clone to its source
database. After the reconnect period the refreshable clone is
disassociated from the source database and reconnecting to the
source database is not allowed.
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 with Automatic
Refresh Enabled 🔗
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 automatic refresh option is only
available when the source database uses the ECPU compute model.
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.
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.
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.
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.
Refreshable Clone Refresh Timing
and Disconnecting 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.
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.
Refreshable Clone Reconnect to 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.
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:
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.