Cloning Oracle Database 12.1 PDBs to get a test PDB required the source PDB to be in read- only mode, which was nearly unacceptable on a production PDB. The new Oracle Database 12.2 technique copies a remote source PDB into a CDB while the remote source PDB is still up and fully functional.
Hot remote cloning requires both CDBs to switch from shared UNDO mode to local UNDO mode, which means that each PDB uses its own local UNDO tablespace.
In addition, hot cloning allows incremental refreshing in that the cloned copy of the production database can be refreshed at regular intervals. Incremental refreshing means refreshing an existing clone from a source PDB at a point in time that is more recent than the original clone creation to provide fresh data. A refreshable copy PDB can be opened only in read-only mode.
Propagating changes from the source PDB can be performed in two ways:
Manually (on demand)
Automatically at predefined time intervals
If the source PDB is not accessible at the moment the refresh copy needs to be updated, archive logs are read from the directory specified by the REMOTE_RECOVERY_FILE_DEST parameter to refresh the cloned PDB.
Let’s see in the Figure, how to do it
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