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## 5.1 Understanding the Installation Choices

Learn about the installation choices in Oracle APEX.

The multitenant database architecture has a multitenant container database (CDB) that includes a root container, `CDB$ROOT`, a seed database, `PDB$SEED`, and multiple pluggable databases (PDBs). Each pluggable database is equivalent to a separate database instance in Oracle AI Database release 11g. The root container, `CDB$ROOT`, holds common objects that are accessible to every PDB utilizing metadata links or object links. The seed database, `PDB$SEED`, is used when creating a new PDB to seed the new database. The key benefit of the multitenant architecture is that the database resources, such as CPU and memory, can be shared across all of the PDBs. This architecture also enables many databases to be treated as one for tasks such as upgrades or patches, and backups.

Tip:

Oracle recommends installing APEX in individual PDBs for the majority of use cases, except for hosting companies or installations where all PDBs utilize APEX and they all need to run the exact same release and patch set of APEX.

When APEX is installed in the CDB, you still install and run APEX applications from individual PDBs. Running APEX applications or accessing an APEX development environment in the `CDB$ROOT` container is not supported.

See Also:

Installing APEX into Different PDBs

Parent topic: Utilizing Multitenant Architecture