Hotfixes are software patches applied to live systems (the ones still running). A hotfix is a single, cumulative package that includes one or more files used to address a problem in a software product (i.e., a software bug).
In the Microsoft SQL SERVER context, hotfixes are small patches designed to address specific issues, most commonly to freshly-discovered security holes. For example, if a select query returns duplicate rows with aggregations, the result may be wrong. This can be fixed by a hotfix.
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