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Oracle in a Nutshell
book

Oracle in a Nutshell

by Rick Greenwald, David C. Kreines
December 2002
Intermediate to advanced content levelIntermediate to advanced
928 pages
85h 29m
English
O'Reilly Media, Inc.
Content preview from Oracle in a Nutshell

Oracle Instances and Databases

Two entities are sometimes referred to as an Oracle database—the instance and the database—and people often confuse them.

In the Oracle world, the term database refers to the physical storage of information, while instance refers to the software executing on the server that provides access to the information in the database. The instance runs on the computer or server; the database is stored on the disks attached to the server, as shown in Figure 1-1.

An instance and a database

Figure 1-1. An instance and a database

The database is physical: it consists of files stored on disks. The instance is logical: it consists of in-memory structures and processes on the server. An instance can connect to one and only one database. Instances are temporal, but databases, with proper maintenance, last forever.

Users do not directly access the information in an Oracle database. Instead, they pass requests for information to an Oracle instance.

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Publisher Resources

ISBN: 0596003366Errata Page