Index make searching faster and you don;t need to do verification for each record. Types of Index 1. Simple Index: on one Column 2. Composite Index: multiple Column 3. Unique Index :No duplication in column 4. Reverse Index: start work in reverse order 5. Function-based Index:you need to perform some function like salary commission of an employee,or average of student marks 6. Bitmap Index:works on less number of values,like status-->active/inactive,gender-->male/female

1. Index Management
Database Administration and Management

2. Need of Index
When we run query (Select marks from student where marks <33);
OR
When we run query (Select sale from employee where salary <5000);
 Frequently verifying conditions
 Frequently assessing
 Assessing multiple records
Index
 Index maintains column data in ascending order
 It also maintain addresses
Why we use Index
 Decrease no. of verification
 Save time
 Better performance

3. Example
Roll_No Name Marks Address Roll_No Marks
1 Ali 45 BWP 5 22
2 Usama 87 LHR 6 30
3 Usman 48 BWP 1 45
4 Ahmed 64 BWP 3 48
5 Amir 22 BWP 4 64
6 Umer 30 LHR 2 87

4. Types of Index
 Simple Index
 Composite Index
 Unique Index
 Reversing Index
 Function based Index
 Bitmap Index
Simple Index
 Index create on single column. e.g., sale from employee table ,marks from
student table, etc.
Query
 Create INDEX IDX_SALARY on employee(sale);
 Searching in index, not table

5. Composite Index
 Index creates on multiple columns on any table.
Query
 Create INDEX idx_s.no_rollNo on students(s.no, rollNo);
Unique Index
 Index creates on columns ----- no duplication
Query
 Create UNIQUE INDEX idx_mobileNo on customers_dtls(mobile);
Reversing Index
 Want to search data frequently looking for highest value.
 Normally List values------- beginning, Highest value---------ending
 Its searching is fast because its work in reversing order.
 Based on Binary tree.------ right to left in b.tree.
 Create INDEX idx_sales_amt on sales(sales_amt) REVERSE;

6. Function based index
 Work on function based.
 Suppose I have a table of employee, and have a column of emp_id,salary,commission
Query
 Select e_id,sal(0.100*sal) from emp
 Create Index idx_sal on emp(sal(0.100*sal))init cap(ename);
Bitmap index
 Bits --------- 0,1
 Less number of values in columns
 E.g.,
 status--active/inactive,
 Gender--male/female
Query
 Create bitmap Index id_gender on customer(gender);
Note:
 All index created based on the binary tree index.