
6
|
Oracle DBA Pocket Guide
NOTE
All of the initialization parameters are described in Ora-
cle in a Nutshell and the Oracle Initialization Parameters
Pocket Reference, both from O’Reilly, as well as in the ap-
propriate Oracle documentation.
System Global Area
The System Global Area (SGA) is the shared memory area
used by the instance to store information that must be shared
between the database and the user processes. The SGA is
composed of at least three main areas: the database buffer
cache, the shared pool, and the redo log buffer. Optionally, it
may also contain the large pool and the Streams pool, if
defined. Figure 2 shows the SGA and its interaction with
other Oracle components.
Figure 2. The SGA and background processes
SGA
Database buffer
cache
Shared pool
Redo log
buffer
Large pool
DBWn CKPT LGWR ARCn
Datafiles
Control files Redo logs
SMON PMON RECO