This post is a part of the series “Did You Know” whereby the purpose is to share some quick key point of a particular concept that helps us to be informed on top of our head or something that we want to be revisited quickly. So, no detailed discussions on the topic but a straight finding about it in a line or two.
The cost of an operator being shown as 0% in SQL Server Query Execution Plan is actually not 0%.
This is due to rounding off because graphical execution plan shows cost as whole numbers.
You can check text-based execution plan to see the cost < 0.5% which are rounded to 0%.
Such negligible numbers are not paid attention during performance optimization for obvious reasons but it’s good to know.