create table grade
(
student_id number(8) not null ,
class_id number(4) not null,
grade varchar2(2),
constraint pk_grade prmary key (student_id ,class_id)
)
most application access this table by student and class_id , which clause should you add to improve query performance??
1）INDEX-ONLY
2）COMPRESS INDEX
3）ORGANIZATION HEAP
4）ORGANIZATION INDEX
肯定是加index，所以选4，但是ORGANIZATION INDEX这个东西从来没见过啊？？
