Did You Know…That 0% Cost in SQL Query Plan is Not Actually 0%

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.

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