I have a complex SQL 2008 R2 Database that should be tuned. I try to add the indexes and with help of e Actual execution plan to check the result. But the problem is that, when I add a index, the execution plan is changed, for my case the KeyLookup value are reduced from 33 % to 19 %, but a new operation appear - with show that take other 20 %. So I replace an operation with 33% for 2 operations with total cost of 40% - but this new 40 % is a percentage from WHAT value – what I need is a measure of total cost of whole T-SQL in some absolute value – like time for execution, CPU usage or other. Is there any value in Execution plan that I can use for that?