This slide is introduced What is index in database system . It's very simple to let you understand what is index pros and cons. there has chinese voice version youtube :) https://www.youtube.com/watch?v=BOBZAMfQfrQ&feature=youtu.be https://www.youtube.com/watch?v=hkl5CcmZ4OI&feature=youtu.be

1. SQL SERVER INDEX
JAJA

2. TOPIC
• WHAT IS THE INDEX OF DATABASE SYSTEM
• CLUSTERED INDEX VS. NONCLUSTERED INDEX
• THE STATISTICS OF INDEX
• THE COVERAGE IDNEX
• WHAT IS INDEX FRAGMENTATION
• CREATE THE RIGHT INDEX

3. WHAT IS THE INDEX OF DATABASE SYSTEM

4. I want to query customer BIG-Data
…5 min …10 min
…30 min…20 min
BEFORE AFTER

5. INDEX IS DECIDED DATA STORAGE STRUCTURE
HAS CLUSTERED INDEXNO INDEX

6. CLUSTERED INDEX VS. NONCLUSTERED INDEX
CLUSTERED INDEX NONCLUSTERED INDEX
CL01 Taipei Ken
WHERE Country=‘Taipei’
Got it CL Key value CL01
Searching …

7. Binary Search Tree (BST)
http://visualgo.net/bst.html

8. CLUSTERED AND NONCLUSTERED INDEX
BASE ON B-TREE

9. ANYTHING IS A DOUBLE-EDGED SWORD
RECORD
INDEX-01
Page-01
INDEX-02
RECORD001
PG01-RECORD001 PG01-RECORD001
RECORD002
PG01-RECORD002 PG01-RECORD002

10. BE CAREFUL INCREASE THE INDEX

11. THE STATISTICS OF INDEX

12. IT’S IMPORTANT
FOR SQL TO GUESS YOUR QUERY RESULT NUMBER

13. DEMO

14. THE COVERAGE IDNEX

15. INCLUDE EVERYTHING YOU USED
SELECT COLUMN
JOIN COLUMN
WHERE CONDITION COLUMN

16. DEMO

17. WHAT IS INDEX FRAGMENTATION

19. DEMO

20. CREATE THE RIGHT INDEX

21. PRINCIPLE
FREQUENTLY USED COLUMNS
COLUMN UNIQUENESS
COLUMN DATA TYPE