why the estimated operator cost of query plan is more than 100 %

Question

Answer 1

Hi AilsaGe,

Could you please share us your table structure (CREATE TABLE …) and some sample data(INSERT INTO …)
along with your expected result? So that we’ll get a right direction and make some test.

Besides,I found a similar issue,please refer to ：Are the cost percentages in this SQL Server plan over 100% for a valid reason?

Best Regards
Echo

Answer 2

Good day guys,

Good day @Ailsa Ge

I gave the same answer in the MSDN forum.

At the MSDN forum the answer which was given is not accurate and it is very common answer, so I will start with this and send to you to read the full explanation in a post I wrote for you.

SSMS only displays what the SQL Server returns.

This is actually the opposite (at least the issue which I am familiar with). The percentage Cost is calculated in the client side, so this is exactly an issue in the SSMS side usually.

As mentioned, I wrote a post which explain the issue and provide some more information:

https://ariely.info/Blog/tabid/83/EntryId/272/SQL-Server-Execution-Plan-shows-cost-of-more-than-100-percentage.aspx

I hope this is useful

----------

Ronen Ariely
Personal Site | Blog | Facebook | Linkedin