DATA2
The DATA1
tablespace consists
of one datafile
The DATA2
tablespace consists
of two datafiles
DATA1
data1_01.dbf data2_01.dbf data2_02.dbf
36 | Chapter 2: Oracle Architecture
Files of a database
There are actually three fundamental types of physical files that make up an Oracle
database:
??? Control files
??? Datafiles
??? Redo log files
These three fundamental types represent the physical database itself. Figure 2-3 illustrates
the three types of files and their interrelationships.
The control file contains locations for other physical files that form the database: the
datafiles and redo log files. It also contains key information about the contents and
state of the database, including:
??? The name of the database
??? When the database was created
??? Names and locations of datafiles and redo log files
??? Tablespace information
??? Datafile offline ranges
??? The log history and current log sequence information
Figure 2-3. The files that make up a database
Control
Files
Identify
Identify
Redo Log Files
Datafiles
Record changes to
Databases and Instances | 37
??? Archived log information
??? Backup set, pieces, datafile, and redo log information
??? Datafile copy information
??? Checkpoint information
In addition to providing fundamental information at startup, control files are also
useful when removing a database.
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