[dba-SQLServer] Execution statistics

Billy Pang tuxedo_man at hotmail.com
Wed Aug 10 20:11:29 CDT 2005


How much more logical reads?  If it is a lot more logical reads, I am 
betting that it might be a problem in the future since the more reads 
translates to higher execution (#of reads is probably more important on a 
slower disk).  Using a new index for a query I thought usually decreases 
reads  in most cases (because don't have to get the data from the table or 
from another "not so good" index which can be more expensive).

I wonder why the logical reads went up even though execution time went down. 
  Maybe the optimizer found that it was cheaper to create an executin plan 
that gets most of the data from the index and the rest from the table?  Was 
the fillfactor of the new index set to low percentage (index created over 
many pages)?

Billy


>From: "Susan Harkins" <ssharkins at bellsouth.net>
>Reply-To: dba-sqlserver at databaseadvisors.com
>To: "SQLList" <dba-SQLServer at databaseadvisors.com>
>Subject: [dba-SQLServer] Execution statistics
>Date: Wed, 10 Aug 2005 18:30:52 -0400
>
>If you an add an index that improves the execution time, but also increases
>the logical reads -- is that a problem for the future? It seems to me that
>as you add data those page hits are going to eventually slow you down,
>despite the index. Am I analyzing this correctly?
>
>Or, do indexes always increase the logical reads -- that would make sense 
>to
>me too.
>
>Susan H.
>
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