Automatic Memory Management (AMM) in 11g

Up to Oracle 9i one of the hectic process was to define the memory parameters (SGA and PGA) and there are some thumb role needs to followed for the each parameters.
Now DBA sit back and relax since Oracle automated the Memory parameter completely on 11g.

Some lights on old versions:
There are just 2 initialization parameters needed for AMM configuration:
Automatic Memory Management Setup:
The DBCA is also allows you to configure automatic memory management during database creation.
We can manually set,  the appropriate MEMORY_TARGET and MEMORY_MAX_TARGET initialization parameters before creating the database or after.

Kindly use the following calculations:
MEMORY_TARGET =  SGA_TARGET  +  GREATEST(PGA_AGGREGATE_TARGET, "maximum PGA allocated")

The following queries show you how to display the relevant information and how to combine it in a single statement to calculate the required value.
-- Individual values.
COLUMN name FORMAT A30
COLUMN value FORMAT A10

SELECT name, value
FROM   v$parameter
WHERE  name IN ('pga_aggregate_target', 'sga_target')
UNION
SELECT 'maximum PGA allocated' AS name, TO_CHAR(value) AS value
FROM   v$pgastat
WHERE  name = 'maximum PGA allocated';


Assuming our required setting was 4G, we might issue the following statements.
Sqlplus “/as sysdba”
#Set the static parameter. Leave some room for possible future growth without restart.
ALTER SYSTEM SET MEMORY_MAX_TARGET=5G SCOPE=SPFILE;

#Set the dynamic parameters. Assuming Oracle has full control.
ALTER SYSTEM SET PGA_AGGREGATE_TARGET=0 SCOPE=SPFILE;
ALTER SYSTEM SET SGA_TARGET=0 SCOPE=SPFILE;
ALTER SYSTEM SET MEMORY_TARGET=4G SCOPE=SPFILE;

#Shutdown and restart the instance
SHUTDOWN IMMEDIATE;
STARTUP;

The database is restarted the MEMORY_TARGET parameter can be amended as required without an instance restart.
ALTER SYSTEM SET MEMORY_TARGET=4G SCOPE=SPFILE;

Dictionary View Informations:
    V$MEMORY_TARGET_ADVICE
    V$MEMORY_CURRENT_RESIZE_OPS
    V$MEMORY_RESIZE_OPS
    V$MEMORY_DYNAMIC_COMPONENTS

When using automatic memory management, the SGA_TARGET and PGA_AGGREGATE_TARGET act as minimum size settings for their respective memory areas. To allow Oracle to take full control of the memory management, these parameters should be set to zero.

The amount of memory allocated to each dynamic component is displayed using the V$MEMORY_DYNAMIC_COMPONENTS view.

COLUMN component FORMAT A30

SELECT  component, current_size, min_size, max_size
FROM    v$memory_dynamic_components
WHERE   current_size != 0;


COMPONENT                      CURRENT_SIZE   MIN_SIZE   MAX_SIZE
------------------------------ ------------ ---------- ----------
shared pool                       197132288  192937984  197132288
large pool                          4194304    4194304    4194304
java pool                          41943040   41943040   41943040
SGA Target                        318767104  285212672  318767104
DEFAULT buffer cache               71303168   41943040   75497472
PGA Target                        104857600  104857600  138412032


The V$MEMORY_TARGET_ADVICE view provides information to help tune the MEMORY_TARGET parameter. It displays a range of possible MEMORY_TARGET settings, as factors of the current setting, and estimates the potential DB Time to complete the current workload based on these memory sizes.

SELECT * FROM v$memory_target_advice ORDER BY memory_size;

MEMORY_SIZE MEMORY_SIZE_FACTOR ESTD_DB_TIME ESTD_DB_TIME_FACTOR    VERSION
----------- ------------------ ------------ ------------------- ----------
        303                .75         3068              1.0038          2
        404                  1         3056                   1          2
        505               1.25         3056                   1          2
        606                1.5         3056                   1          2
        707               1.75         3056                   1          2
        808                  2         3056                   1          2


Top 25 Oracle Initialization Parameters
The following list is my list of the top 25 most important initialization parameters, in order of importance. Your top 25 may vary somewhat from my top 25 because everyone has a unique business, unique applications, and unique experiences.