By default, the database engine automatically takes snapshots in the root container only. Such snapshots cover the root container as well as all open PDBs belonging to it. From version 12.2 onward, you can control whether the database engine automatically takes also PDB-level snapshots through the dynamic initialization parameter AWR_PDB_AUTOFLUSH_ENABLED. In case you want to enable that feature, you have to carry out two operations:
- Set the initialization parameter AWR_PDB_AUTOFLUSH_ENABLED to TRUE (the default value is FALSE) either in a specific PDB or, if you want to enable it for all PDBs, in the root container.
- Set the snapshot interval at the PDB level.
Note that to enable automatic PDB-level snapshots it’s necessary to set the snapshot interval because the PDB-level default is 40,150 days! Hence, if you don’t change it, the database engine will never take them.
