http://www.sqlservercentral.com/blogs/vinaythakur/2009/10/09/select-count_28002A002900_/

Printed 2014/07/29 05:22AM

Select count(*)

By Vinay Thakur-585143, 2009/10/09

 

Today I was reading(I always read Paul Randal).

http://www.sqlskills.com/BLOGS/PAUL/post/Which-index-will-SQL-Server-use-to-count-all-rows.aspx

I learned that whenever you query select count(*) it will select the the best plan... as

if no index ---no option -table scan

INDEX: choose the smallest possible index(if has multiple index) to achieve the lowest I/O cost.

you can also test this with

set statistics io on

Thanx.

Vinay


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