“Sometimes there was a Situation where you have to create two different schema in the same databases,but both with the same name.”
A typical example is in this case of SIEBEL applications which have a specific schema name – SIEBEL, So if you want to install two SIEBEL applications in the same database,
we always think it’s not possible since you can’t have two schema named SIEBEL in the same database.
SIEBEL IP17 release also certified with this 12c feature.
what are your choices?
you could create two different databases. In fact, prior to Oracle Database 12c that was your only choice. But with two different databases comes two different sets of overheads – two Oracle instances (the memory areas such as SGA and the processes such as pmon and smon) which consume memory and CPU cycles in the host. The more databases you have, the more the CPU and memory usage – all because you want to create multiple schema in the same name.
But now this is not any more, in the multi-tenancy option in Oracle Database 12c. Instead of creating a physical database for each SIEBEL schema you want to create, you can create a virtual database for each schema. Each virtual database behaves like an independent database, but runs on the top of a real , physical database which may be hidden from the end users. These virtual databases are called Containers. The physical database that houses these containers, is known as a Container Database (CDB).
You can pull out or “unplug” a container from one CDB and place it or “plug” it into another CDB. This is why a container is also known as a Pluggable Database .as per client perspective the PDBs are just regular databases.
Do you know ?
It is NOT necessary that the database be created as a CDB with PDBs inside it. You can also create a database exactly how it was (non- CDB) in the privious versions. but there is no cost to create exactly one PDB inside a CDB.
To find out if the database has been created as a CDB or not, just check the column called CDB in the view V$DATABASE.
select cdb from v$database;
In next article we will explain, how to create a database as a PDB.
Happy reading !