The question:
I’m learning a little bit about Oracle Database. As I understand:
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In previous versions of Oracle DB (versions <= 11ng), each DB should be installed in a
separate server.- Is this statement true? We can’t create more than of one database in each instance of Oracle installation? or I’m missing something here.
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To take care of the problem, oracle updated its architecture and introduced the pluggable databases.
- Why not just using the same architecture of other DBMS systems like MySQL whre you can have N number of databases in you single installation of DBMS?
I’m guessing that I’m not fully understanding the first statement as I never had any experiences with Oracle Database.
The Solutions:
Below are the methods you can try. The first solution is probably the best. Try others if the first one doesn’t work. Senior developers aren’t just copying/pasting – they read the methods carefully & apply them wisely to each case.
Method 1
Two things going on here:
First, Oracle defines “database” differently than other “databases” like MySQL. When Oracle talks about a database, they mean the physical instance of the software, data files, and processes that run on on the server. Each database instance may house hundreds or thousands of individual users/schemas, each with their own tables and other objects. It is possible to run multiple database instances on a single server – even using different versions of the software simultaneously. Operating multiple instances/databases – usually but not always of the same version – on a single server is quite common, actually.
Most other database engines equate “database” with a single schema of objects, and often only support one installation of the software on an individual server, though they may house hundreds or thousands of users/schemas.
Second, Oracle’s pluggable databases (introduced in Oracle 12c) are a virtualization of the database instance (the running processes, data files, etc.) that allows them to share some common, system-level resources. A container database (CDB) manages those system level resources, and may host many pluggable databases (PDB). A single server may host multiple container databases of different software versions, each with their own pluggable databases. Each pluggable database may contain hundreds or thousands of users/schemas. The pluggable database architecture allows for consolidation of compute and storage resources: a higher density architecture that makes more efficient use of both on-premise and cloud hardware.
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