Here the following is an example SQL shows you that select the maximum emp_address which is not indexed in the EMPLOYEE table with 3 million records, the emp_grade is an indexed column.
select max(emp_address) from employee a
where emp_grade<4000
![[IMG]]()
As 80% of the EMPLOYEE table’s records will be retrieved to examine the maximum emp_address string. The query plan of this SQL shows a Table Access Full on EMPLOYEE table...
How to index SQL with aggregate function SQL for Oracle?
select max(emp_address) from employee a
where emp_grade<4000
![[IMG]](http://live.staticflickr.com/65535/51894321053_eda5aed07e_b.jpg)
As 80% of the EMPLOYEE table’s records will be retrieved to examine the maximum emp_address string. The query plan of this SQL shows a Table Access Full on EMPLOYEE table...
How to index SQL with aggregate function SQL for Oracle?