Keep table and index in Memory - Oracle

Some useful commands to keep indexes or table in oracle buffer pool.
it may be useful for your application performance  if you have some key tables that are many and many times requestes  from your application.  

To keep tables in memory
alter table LOGICAL_AGGREGATION storage (buffer_pool keep);
alter table NGN_ENTITY_NODE storage (buffer_pool keep) ;

remember to keep table indexes also:
alter INDEX indexname storage (buffer_pool keep) ;