Step 5 - Managing Memory Parameters
Learn Oracle - Managing Memory Parameters
Some initialization parameters, referred to here as memory parameters, determine the
total size of the system global area (SGA) and the program global area (PGA), and of
the subcomponents of the SGA. The settings of memory parameters can affect the
performance of your database. When Oracle DBA install your database, these parameters are
tuned to meet the requirements of the environment that Oracle DBA specify.
If Oracle DBA enabled Automatic Shared Memory Configuration when Oracle DBA configured your
database, Oracle automatically sizes the subcomponents of the SGA, which include the
shared pool and buffer cache. Oracle recommends that Oracle DBA enable memory auto
If Automatic Shared Memory Management is disabled, Oracle DBA can enable it on the
Memory Parameters page. You can navigate to this page from the Administration page
by clicking Memory Parameters under the Instance heading. From this page Oracle DBA can
enable or disable Automatic Shared Memory Management and view your SGA and
PGA memory settings from their property pages.
Modifying Memory Parameters
To modify the size of an SGA subcomponent without bringing your instance down,
Oracle DBA can disable Automatic Shared Memory Management on the Memory Parameters
If Oracle DBA choose to modify
your memory settings manually, you can enter new sizes and apply changes
dynamically while the instance is up. You can also do so from the Current property
page on the Initialization Parameters page. However, there are some restrictions on
dynamic modification of memory parameters.
To make changes to memory parameters persistent across instance startup and
shutdown, Oracle DBA must alter your parameter file. Oracle DBA can do so by navigating to SPFile
property page from the Memory Parameters page and making your changes there.