OCA /OCP Oracle Database 11g A ll-in-One Exam Guide- P95:There is an ever increasing demand for staff with IT industry certification. The benefits to employers are significant—they can be certain that staff have a certain level of competence—and the benefits to the individuals, in terms of demand for their services, are equally great. Many employers are now requiring technical staff to have certifications, and many IT purchasers will not buy from firms that do not have certified staff. | OCA OCP Oracle Database 11g All-in-One Exam Guide 896 Automatic Memory Management The Automatic Memory Management mechanism lets the Oracle instance manage server memory usage as a whole by setting one parameter MEMORY_TARGET. This takes the automatic PGA management enabled with PGA_AGGREGATE_TARGET and the automatic shared memory management enabled with SGA_TARGET a step further by letting Oracle transfer memory between PGAs and SGA on demand. TIP To enable automatic memory management set the one parameter MEMORY_TARGET and do not set any of the other parameters listed previously with the exception of LOG_BUFFER though this too can often be left on default. Automatic memory management is not just a tool to make database administration easy. It will often give big performance benefits as well. Many databases will experience different patterns of activity at different times which could benefit from different memory configurations. For example it is not uncommon for a database used for order processing to experience a very light transaction processing workload during most of the month and then a heavy query processing workload during month-end reporting runs. Transaction processing will typically not be demanding on PGA memory but will require a large database buffer cache. Query processing will often require large PGA allocations but not much buffer cache. EXAM TIP The MEMORY_TARGET parameter is dynamic it can be adjusted without shutting down the instance but only within a limit set by another parameter MEMORY_MAX_TARGET. This is static so it can only be raised by adjusting with the SCOPE SPFILE clause and restarting the instance. Manually transferring memory between SGA and PGA in response to changing patterns of activity is not a practical option and many systems will not be able to allocate enough memory to both concurrently to satisfy their peak demands. Automatic memory management is able to transfer memory between SGA and PGA as necessary to optimize .
