August 5, 2002 at 4:40 am
Hi!
Could someone explain how can i calculate (and compare) the COST (in percent values) when running 2 diferent queries, both achiving the same result?
I've been reading about performance tips, and all refer that "if you do this (...) you'll get a 30% speed up...)" but i cant actualy see that diference anywhere!
Query analizer only shows "Estimated Subtree cost: 1,0000000%" for each operation: should i SUM all the "Estimated costs" ???
Or there is any king of formula to calculate the total cost, therefore providing a base value to compare to other execution plans?
Thanks!
@Rodrigues
LabDev
labdev@iol.pt
August 5, 2002 at 9:17 am
I usually do two things.
1. Measure the time (use select getdate() around the queries) on the server or client.
2. Check the subtree cost. The percentage cost will always be 1 for the final step because all steps have added to 100%. You can use this to check indivual steps to get their percentage.
Steve Jones
August 5, 2002 at 9:52 am
Hi, Steve!
I can't fully understand that...
It means that i must read, say, from right to left (steps), while calculating individual percentages of all steps???
@Rodrigues
LabDev
labdev@iol.pt
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