Oracle Multitenant architecture improves database integration efficiency through CDB/PDB structure, unified management operations and reduces duplicate maintenance; 1. Upgrade only needs to be performed once at the CDB layer, and all PDBs automatically inherit new versions; 2. Multiple PDBs share resources while implementing data isolation, supporting independent opening and closing, cloning and migration; 3. Backup and recovery can be carried out at the CDB level or PDB level, but partial recovery and cross-platform cloning need to pay attention to log synchronization and compatibility; 4. Permissions are divided into public users and local users, which are suitable for centralized management and application-specific scenarios; this architecture simplifies daily DBA tasks, but also puts forward higher requirements for security management, fault window control and monitoring and diagnosis.

Oracle Multitenant architecture (CDB/PDB) has changed the way database management and integration is used to allow a container database (CDB) to accommodate multiple pluggable databases (PDBs), thereby significantly improving resource utilization and management efficiency. For DBA, this architecture brings operational simplification and introduces new management ideas.

Unified underlying management to reduce duplicate operations

In traditional non-multi-tenant environments, each database is an independent instance, and maintenance work such as patching, upgrading, backup and recovery need to be processed one by one. Under the Multitenant architecture, these tasks can be completed uniformly at the CDB layer, affecting all PDBs.

• Advantages : For example, you only need to upgrade the CDB once during upgrade, and all PDBs automatically inherit the new version, saving you the trouble of upgrading individually for each database.
• Challenge : But it also means that once a CDB has problems, it may affect multiple PDBs, so the maintenance window needs to be arranged more carefully.

More flexible resource integration and isolation

The Multitenant architecture supports isolating data from multiple applications or business units into their respective PDBs while sharing underlying resources. This is very useful for consolidating multiple small databases.

• Enterprises can integrate multiple databases in development, testing and production environments into one CDB, saving hardware and licensing costs.
• Each PDB can be opened and closed, cloned, and migrated independently, which is suitable for rapid deployment or snapshot testing.

For example, you can clone a test environment from the production PDB in minutes without re-importing the data.

Backup and recovery strategies are more efficient but also more complex

When using RMAN for a holistic CDB backup, data for all PDBs and root containers are included. But you can also choose to only backup a specific PDB.

• If only one PDB needs to be restored, DBAs need to be familiar with how to perform "partial recovery" in a CDB environment.
• When using "hot cloning" or "remote cloning" technology, you should also pay attention to the synchronization of archived logs to avoid data inconsistencies.

This is particularly easy to ignore, especially when cross-platform or cross-version cloning, improper configuration may cause the PDB to fail to open.

Changes in permission model and monitoring methods

In CDB, there are two types of users: Common User and Local User. DBAs need to be clear about the permission boundaries between the two.

• Public users can be used in all PDBs and are suitable for centralized management.
• Local users can only use it in one PDB, suitable for application-specific accounts.

In terms of monitoring, although you can view the running status of the entire CDB through the V$ view, if you want to deeply analyze the performance problems of a PDB, you also need to switch to the PDB context to execute diagnostic commands.

Basically that's it. The Multitenant architecture does simplify the daily work of many traditional DBAs, but it also requires DBAs to better understand the structural logic of CDB/PDB, especially in key links such as security, permissions, and backup and recovery.

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