* Description: Knowledge of SGA/PGA auto memory management [AMM] parameters.
* Compatiablity: RDBMS 11g, 12c
* Date: 11:52 AM EST, 03/21/2017

<1> Oracle Auto Memory Management [AMM]:
     |__ If following parameters are setting as below, which mean AMM feature is not enabled:
         |__ memory_max_target=0   ==> It is an initial parameter, which needs database reboot to make alive.
             memory_target=0       ==> It is an dynamic parameter, which can be changed when database is up and running.
<2> How to enable AMM:
     |__ SQL> alter system set memory_max_target=20G scope=spfile; -- This command allows Oracle instance to use 20GB maxmium of whole total physical memory, such as 64GB.
         SQL> shutdown immediate;
         SQL> startup;
         SQL> alter system set memory_target=15G scope=spfile; -- This command introduces Oracle instance to use 15GB out of 20GB memory_max_targe.
                                                               -- Caution: even database uses 15 out of 20GB, Oracle still occupies extra 5GB, which taken from OS.

<3> Why we need memory_max_target when we have memory_target?
     |__ Having this option to adjust memory_target dynamically you can find what is the suitable memory target for the particluar database. 
         For example, it is 12G for our example then at next outage or restart set memory_max_target=12G and leave memory_target=12G.