Data Dictionary Storage in a CDB
The data dictionary that stores the metadata for the CDB as a
whole is stored only in the system tablespaces. The data dictionary that stores
the metadata for a specific PDB is stored in the self-contained tablespaces
dedicated to this PDB. The PDB tablespaces contain both the data and metadata
for an application back end. Thus, each set of data dictionary tables is stored
in its own dedicated set of tablespaces.
Current Container
For a given session, the current container is the one in which
the session is running. The current container can be the root (for common users
only) or a PDB.
Each session has exactly one current container at any point in
time. Because the data dictionary in each container is separate, Oracle
Databases uses the data dictionary in the current container for name resolution
and privilege authorization.
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