Tuesday, 21 July 2009

The Database

The Database

The database consists of two parts the database and the instance. So what is the difference?

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 one or more instances.

No comments: