What is SQL Server latch-free architecture in In-Memory OLTP internals?

In-Memory OLTP eliminates locks and latches using optimistic concurrency and versioning structures.

Hekaton (In-Memory OLTP) removes traditional locking mechanisms and replaces them with optimistic concurrency control using multi-version rows. Each row version contains timestamps and transaction metadata. Reads never block writes and vice versa. Indexes are memory-optimized (hash or range), and storage is managed through checkpoint files and delta files. This design minimizes contention and enables extreme concurrency.