Oracle - Aumento da SGA

alter system set sga_max_size = 800m scope=spfile;
alter system set sga_target = 800m scope=spfile;
alter system set SHARED_POOL_SIZE = 0 scope=spfile;
alter system set DB_CACHE_SIZE = 0 scope=spfile;
alter system set DB_KEEP_CACHE_SIZE = 0 scope=spfile;
alter system set LOG_BUFFER = 0 scope=spfile;
alter system set LARGE_POOL_SIZE = 0 scope=spfile;
alter system set JAVA_POOL_SIZE = 0 scope=spfile;

Depois tem que dar shutdown immediate e startup