What is the difference between a database and an instance?
February 2nd, 2006 By Eddie Awad
To understand the difference between a database and an instance, we need to know the basic definition of each and the relationship between them.
Definition:
- A database is a set of files stored on disk.
- An instance is a collection of Oracle background processes and shared memory.
Relationship:
- An instance can mount and open one and only one database.
- A database may be mounted and opened by one or more instances.
For example, in the case of Real Application Clusters (or RAC) a database is usually mounted and opened by many instances.
February 2nd, 2006 at 12:35 pm
As the name instance says an instance is the memory instantiation of a physical database ;-) so *starting a database* is not the correct phrase -you just *create an instance* of it;
Karl