June 12, 2010 at 5:16 am
I have a table having 84000+ records, I am planning to consider index on this table. I am putting few details of execution plan below: -
When table has no Index: -
Select * from <table name>;
Table scan happens,
Estimated I/O cost = 0.517278
Estimated CPU cost = 0.0930076
Estimated operator cost = 0.610285(100%)
Estimated sub-tree cost = 0.610285
When table has clustered Index on id column: -
Clustered Index scan happens,
Estimated I/O cost = 0.517199
Estimated CPU cost = 0.0930861
Estimated operator cost = 0.610285(100%)
Estimated sub-tree cost = 0.610285
When table has Non-clustered Index on id column: -
Table scan happens,
Estimated I/O cost = 0.517199
Estimated CPU cost = 0.0930861
Estimated operator cost = 0.610285(100%)
Estimated sub-tree cost = 0.610285
Now my question is without indexing estimated CPU cost 0.0930076 is very less compare to others 0.0930861 and estimated I/O cost 0.517278 is higher than others 0.517199. Then which Index I need to create, how can I consider these values? I am bit confused about this, please help.
June 12, 2010 at 7:06 am
Please don't cross post. It just wastes peoples time and fragments replies.
No replies to this thread please. Direct replies to: http://www.sqlservercentral.com/Forums/Topic936426-360-1.aspx
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
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