Advisory view estimate the Memory target , SGA and PGA
Memory target Advisory: It is used to check the memory tuning which is introduced in 11g Oracle. MEMORY_TARGET parameter is the combination of SGA plus PGA. You don’t need to set SGA_TARGET parameter and PGA_TARGET parameter desperately in Init parameter File.
Note: If you set SGA_target or PGA Target value instead of 0 then it is consider as minimum value of SGA or PGA during instance startup and maximum value is controlled by Memory_target parameter
Memory Target = SGA + PGA
select memory_size,memory_size_factor,estd_db_time from v$memory_target_advice;
SGA Advisor: It will provide the data of SGA tuning how much space utilization in memory with the current environment and what will happen if we increase it. Sga_target is the parameter defined in Parameter file for set the SGA size. SGA_target automatically assign the value to db_cache, large_pool, shared_pool, java_pool.
SGA Target = SHARED_POOL + DB_CACHE + LARGE POOL + JAVA POOL
select sga_size, sga_size_factor, estd_db_time from v$sga_target_advice;
PGA Advisor: It is memory needed by session to perform its activity. It is set by PGA_TARGET parameter in oracle.
select pga_target_for_estimate,pga_target_factor,estd_extra_bytes_rw from v$pga_target_advice;