SET NOCOUNT ON usage

Question

Inspired by this question where there are differing views on SET NOCOUNT...

Should we use SET NOCOUNT ON for SQL Server? If not, why not?

Answer 1

It took me a lot of digging to find real benchmark figures around NOCOUNT, so I figured I'd share a quick summary.

• If your stored procedure uses a cursor to perform a lot of very quick operations with no returned results, having NOCOUNT OFF can take roughly 10 times as long as having it ON. ¹ This is the worst-case scenario.
• If your stored procedure only performs a single quick operation with no returned results, setting NOCOUNT ON might yield around a 3% performance boost. ² This would be consistent with a typical insert or update procedure. (See the comments on this answer for some discussion about why this may not always be faster.)
• If your stored procedure returns results (i.e. you SELECT something), the performance difference will diminish proportionately with the size of the result set.