Why do we need to gather stats. I am having a table let it be ABC.Every day there is insertion of 10k records in it. So as per my knowledge oracle automatically gather stats for every new record at time of insertion.Even indexes are rebuild on every insertion. So de we really need to gather stats manually?
Stats are not automatically gathered on every insert and index are not rebuild on every insert. Stats gather is very important to get good SQL performance. CBO generate optimal SQL plan for better performance . Read more about CBO and SQL Plan