When creating a table, youcan specify the tablespace in which to create
it. Oracle will then find space for it in one of the datafiles that make up the tablespace.
Figure 2-1. An instance and a database
Oracle Instance
Database
Server
Oracle Database
An Oracle instance consists of
processes and memory on the
database server
An Oracle database consists of physical
files on the disk
Databases and Instances | 35
Figure 2-2 shows the relationship of tablespaces to datafiles for a database.
This figure shows two tablespaces within an Oracle database. When you create a
new table in this Oracle database, youmay place it in the DATA1 tablespace or the
DATA2 tablespace. It will physically reside in one of the datafiles that make up the
specified tablespace.
Oracle??™s default tablespaces for all types of tables are locally managed tablespaces as
of Oracle Database 10g Release 2. Locally managed tablespaces enable creation of
bigfile tablespaces that can leverage 64-bit systems and their ability to manage ultralarge
files.
Oracle9i introduced the concept of Oracle Managed Files (OMFs), which enable
your database to automatically create, name, and delete, where appropriate, all the
files that make up your database.
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