How to improve SELECT performance on a big ORACLE view? I cannot use a materialized view for the base table data changed frequently. There are about 0.6 million rows in the_big_view. The query I need to do is: SELECT * FROM the_big_view WHERE student_number='*****', which returns arbitrary rows of data.

If I add an "ORDER BY student_number" clause in the "CREATE VIEW the_big_view AS ...", does that do good?
No, an order by in the view will not help. You may want to do two things. First of all you should ensure that student_number is indexed in the underlying table. Plus if the big view joins multiple tables you should ensure that the join columns are indexed. 

Second you may want to use a number like this:

WHERE student_number=123456


instead of 

WHERE student_number='123456'


if student_number is numeric to avoid type conversions.