Oracle 12c and Multi-Tenant Architecture — is It Worth It?

A persistent question Oracle users face when deciding to move their databases to Oracle 12.1 is whether to opt for the multi-tenant architecture — a fundamental change in this version of the Oracle Database. The question arises because the multi-tenant architecture changes may affect user created scripts that control backups and monitoring, and because of the potential to incur new licensing costs if more than one pluggable database is created per container.  Users may decide not to upgrade or to postpone a decision to avoid these changes.

Multi-tenant architecture revisited

Multi-tenant architecture divides the database into three parts:

• A container database (CDB) that contains metadata and runs a single set of background processes for constituent databases.
• The constituent or pluggable databases (PDB) that plug into a CDB. These databases contain the schemas and data for your applications.
• A seed PDB that is used as a template by the CDB to create a PDB.

“In a nutshell, the new design splits today’s database into two separate entities, an act Llewellyn called ‘architectural separation.’ One portion, often referred to as the Root or the container database, will hold all the functionality and metadata required to run the database itself. The second portion will be the user’s database and it will be independent from the container database.” — Joab Jackson, Computerworld

Given such an architecture, end users can benefit from the cost savings of extreme consolidation of databases without sacrificing individual scalability and growth of each child database (PDB). Let’s not forget the fact that each pluggable database need not be separately patched, upgraded, monitored, backed up, or optimized. Since the PDB files are hosted under the same CDB these files share a common System Global Area (SGA). This enables the management of multiple pluggable databases as a single unit.

I just have a single-production database

This is where it gets interesting. The fact is that a container database may have zero, one, or more pluggable databases. One of the little-known facts is that licensing costs for the multi-tenant architecture kicks in only when you opt for more than one pluggable database within a CDB.

If you upgrade to Oracle 12.1 and create only a single PDB then there are no licensing fees. You get the benefits of Oracle 12.1 and its CDB architecture.

What if I stay with my current version?

If you have a single-production database and are using a version of Oracle lower than Oracle 12.1 then you have the following alternatives:

1. Stay with your current version of Oracle
2. Upgrade to Oracle 12.1 with a non-CDB architecture
3. Upgrade to Oracle 12.1 and use the CDB architecture

Oracle has deprecated the non-CDB architecture and may discontinue support for this in future versions. Considering this point alone, options 1 and 2 are not recommended.

The third option, however, is highly recommended, as you:

• Benefit from the numerous advantages and features of Oracle 12.1
• Pay zero license fee
• Prevent your database from being stuck in an obsolete architecture with zero support from Oracle

If you have more than one production database and want a means to consolidate and cut costs, then using the CDB architecture in 12.1 could be an option that you may want to evaluate. You may want to analyze this by carrying out a cost benefit analysis and determining the return on investment (ROI) of investing in the licensing fee of the CDB option.

If would like more information on the new features of Oracle 12.1 or need help moving your databases to Oracle 12.1, please contact us today or download our new white paper, Compelling Reasons to Upgrade to Oracle 12.1. Datavail is a specialized IT services company focused on Data Management with solutions in BI/DW, analytics, database administration, custom application development, and enterprise applications. We provide both professional and managed services delivered via our global delivery model, focused on Microsoft, Oracle and other leading technologies.

For additional resources you can also read the blog: Preparing for the Move to Multitenant Architecture.