Show parameter memory_target;The MEMORY_MAX_TARGET parameter defines the maximum RAM that Oracle can use in case of heavy workloads. Example, if MEMORY_TARGET is set to 10 GB and MEMORY_MAX_TARGET is set to 20 GB, then during heavy workloads, Oracle instance can max take upto 20 GB RAM
show parameter memory_max_target;
show parameter sga_target; show parameter sga_max_size;
show parameter pga_aggregate_target; show parameter pga_aggregate_limit; so, Instance Size=SGA_TARGET+PGA_AGGREGATE_TARGET