Guru's Guide to SQL Server Architecture and Internals, The

The Memory Managers

Rather than embed all of the complexities of memory management into the BPool itself, SQL Server spreads it across five major memory manager classes. This allows different memory consumers to allocate and manage memory independently of one another while still using a shared, managed memory pool.

Understand that a handful of allocations bypass these managers altogether. The transaction log implements its own caching mechanism, as does the backup/restore facility. There are other examples as well. Rather than go through a memory manager, these allocations come straight from the OS via calls to VirtualAlloc.

The five managers are the Connection, Query Plan, Optimizer, Utility, and General memory managers. Each is responsible ...