Enlighten me about INCLUDE on indexes
what you read and did is correct ?

Suppose, you have no index on user table,then

CREATE INDEX ix_bla on USERS (Reputation) 
INCLUDE (Id, DisplayName)
WHERE Reputation &gt; 400000;


This index is ok.

But this was not the point @Erik wanted to demonstrate.

According to that blog,suppose you already have any such index like,

CREATE UNIQUE NONCLUSTERED INDEX Users_400k_Club
 ON dbo.Users ( DisplayName, Id )


And you are require to create filtered index on Reputation then just be mere mentioning it in Include will do the job and save from creating expensive index.

so he dis this,

CREATE UNIQUE NONCLUSTERED INDEX Users_400k_Club
 ON dbo.Users ( DisplayName, Id )
 INCLUDE ( Reputation )
 WHERE Reputation &gt; 400000
 WITH ( DROP_EXISTING = ON );


Filtered Indexes: Just Add Includes This is the new point about Filtered Index that he wanted to show.