Question

I’ve read about primary, unique, clustered indexes etc. But I need to understand it via an example.

The image below is the auto-generated aspnet_Users table captured from SQL Server Web Admin Panel.

Auto-generated ASP.NET Users Table http://eggshelf.com/capture.jpg

Taking this as a model; I will create a custom table called Companies and let’s say the fields are: ID, Name, ShortName, Address, City, Country.. No values can be duplicate for ID, Name and ShortName fields.

What is your approach on creating indexes for this table? Which should be clustered or non-clustered? Are indexes below logical to you?

Index          Columns         Primary    Unique    Clustered    ign.Dup.Keys   Unique Key
------------------------------------------------------------------------------------------
PK_ID          ID              True       True      False        False          False
Comp_Index     Name,ShortName  False      True      True         False          False

regards..

Answer 1

Go and get a quick overall understanding of SQL Server Indexes by reading Brad’s Sure Guide to Indexes

Typically, having not performed any query analysis your starting point will be:

• The Primary Key column can make a good candidate for the Clustered Index (often dependant on data type used and key width).
• You should create Non-Clustered indexes on Foreign Key Columns.
• You should create Non-Clustered indexes on SARG columns from your queries.

Then take a look at these generic index tips.