Microsoft® SQL Server 2012 Unleashed

The Lock Manager

The responsibility for ensuring lock conflict resolution between user processes falls on the SQL Server Lock Manager. SQL Server automatically assigns locks to processes to guarantee that the current user of a resource (for example, a data row or page, an index row or page, a table, an index, or a database) has a consistent view of that resource, from the beginning to the end of a particular operation. In other words, what you start with is what you work with throughout your transaction. Nobody can change what you are working on in midstate, thereby ensuring the consistency of your transaction.

The Lock Manager is responsible for deciding the appropriate lock type (for example, shared, exclusive, update) and the appropriate ...