Presentation as used during my session on Indexing basics at the SQL Server Bangalore UG meet attended by over 50 odd SQL Server enthusiasts.

1. Indexing
Let’s rediscover the Basics

2. Introduction
• Sourabh Agarwal
• Premier Field Engineer – Microsoft Services
• Blogs: www.sqluninterrupted.com
• Facebook: www.facebook.comtroubleshootingsql,
www.facebook.comsqlserverfaq
• Twitter: @napsterreturns

3. Base Table
• Heap Or Clustered Index
• If Heap, Managed by the IAM
• If Clustered managed as a Balanced Tree.

4. HEAP
• Random (Non Sequential)
collection of Pages
• Managed through the IAM (Index
Allocation Map)

5. Clustered Indexes
• Balanced Tree Structure
• Index Pages on Root and
Intermediate Pages
• Actual Data Pages as leaf Pages
• ** IAM page is still maintained

6. DEMO
• HEAP Table Structure
• Clustered Index Structure

7. Non-Clustered Indexes
• Created On Top of the base Tables
• Separate Structures, occupies space in the SQL Data File
• Can be
• Unique Non Clustered Indexes
• Non-Unique Non Clustered Indexes
• Single Columns/Multi Columns
• INCLUDE can be used to store other column values in the index.

8. Non-Clustered Index on
Non-leaf
HEAP
Level
Non-clustered
Index Pages
• Index Keys on Root or
Intermediate Pages
.
. .
. .
. .
.
Leaf
. . . . • Index Keys + Row ID in
Level
. . . . the Leaf Pages
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. .
. .
. .
. .
. .
. Data
.
. .
. .
. .
. .
. .
.
Pages

9. Non-Clustered Index On Clustered
Index Table
• Index Key Values on the Root and
Intermediate levels.
• Non-Clustered Index Key + Clustered
Index Key Value

10. DEMO
• Non-Clustered Indexes on Heap
• Non-Clustered Indexes on Clustered Index Tables
• Non-Clustered Indexes with include Columns.