When SQL Server detects a scenario in which memory grant usage is inefficient, the MemoryGrantWarning element is added to actual Showplan XML. This element contains information about initial request, granted memory, and maximum used grant. The most common scenario for this warning is when a query is using only a fraction of allocated memory grant. The other scenarios are rare, and relevant behavior of SQL Server may change in future versions.
Article ID: 3172997 - Last Review: Nov 16, 2016 - Revision: 1