microsoft.public.sqlserver.server

Author

Index question

Samir Badaoui

2002-10-05, 9:07 pm

Hi friends,
I am new to sqlServer,
I wander to know : if I have a table tab1 with index i1_tab1 on col1 asc.
Defining an other index I2_tab1 on tab1 (col1 desc) can help for prformance
in some situations ? or definning just 1 index ascendant is sufficient.
Thanks for any help

Dan Guzman

2002-10-05, 9:07 pm

A single column index can be accessed efficiently in either ascending or
descending order so the descending index is redundant. It may be
appropriate to specify descending on some of the columns in a composite
index in order to satisfy the ORDER BY clause in queries.

See the Books Online (createdb.chm::/cm_8_des_05_5n77.htm) for details.

Hope this helps.

Dan Guzman
SQL Server MVP

-----------------------
SQL FAQ links (courtesy Neil Pike):

http://www.ntfaq.com/Articles/Index...epartmentID=800
http://www.sqlserverfaq.com
http://www.mssqlserver.com/faq
-----------------------

"Samir Badaoui" <sbadaoui@videotron.ca> wrote in message
news:ejTf9.63870$W24.1534176@wagner.videotron.net...
> Hi friends,
> I am new to sqlServer,
> I wander to know : if I have a table tab1 with index i1_tab1 on col1
asc.
> Defining an other index I2_tab1 on tab1 (col1 desc) can help for
prformance
> in some situations ? or definning just 1 index ascendant is
sufficient.
> Thanks for any help
>
>

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