May 23, 2013 at 12:28 am
Good Day.
On our SQL Server 2008R2 we identified an inefficient query . We ran it through the Database Tuning Adviser and advised us to add 2 indexes . The same columns were identified , but the only difference was the order of the columns . This makes no sense to me . Any ideas ?
May 23, 2013 at 12:39 am
Index column order is important
http://sqlinthewild.co.za/index.php/2009/01/19/index-columns-selectivity-and-equality-predicates/
That said, test the indexes, if they help, implement them (or one). If they don't, then don't.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability
May 23, 2013 at 12:42 am
lianvh 89542 (5/23/2013)
Good Day.On our SQL Server 2008R2 we identified an inefficient query . We ran it through the Database Tuning Adviser and advised us to add 2 indexes . The same columns were identified , but the only difference was the order of the columns . This makes no sense to me . Any ideas ?
I've always felt that looking first at improving the query (not all methods for constructing queries that return the same results perform the same) and then think about adding indexes was the correct approach.
My thought question: Have you ever been told that your query runs too fast?
My advice:
INDEXing a poor-performing query is like putting sugar on cat food. Yeah, it probably tastes better but are you sure you want to eat it?
The path of least resistance can be a slippery slope. Take care that fixing your fixes of fixes doesn't snowball and end up costing you more than fixing the root cause would have in the first place.
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[url url=http://www.sqlservercentral.com/articles/St
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