Lock escalation

Lock escalation is the process of converting many row/page locks into table locks. Every lock is a memory structure too many locks would mean, more memory being occupied by locks. To prevent this from happening, Microsoft SQL Server dynamically determines when to perform lock escalation. When making this decision, SQL Server takes into account the number of locks that are held on a particular scan, the number of locks that are held by the whole transaction, and the memory that is being used for locks in the system as a whole.