Oracle 10g: Oracle automatic memory management

In Oracle10g memory can be managed automatically by setting parameter sga_target.

Oracle will then manage parameters like: db_cache_size, shared_pool_size, java_pool_size, large_pool_size. You will see new '__' parameters created by Oracle:
__db_cache_size, __shared_pool_size, __java_pool_size, __large_pool_size, these are now dynamically managed.

Check what sga_target is set to:

SQL> sho parameter sga_target

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
sga_target                           big integer 1216M

To change sga_target:

$ sqlplus "/ as sysdba"

SQL> alter system set sga_target = 2000M scope = spfile;

System altered.

SQL> shutdown immediate

SQL> startup

To disable Oracle automatic memory management:

SQL> alter system set sga_target = 0 scope = spfile;

System altered.

SQL> shutdown immediate

SQL> startup