DMV revisited.. PART 2
PAGEIOLATCH is related to IO issues, while PAGELATCH is not related to IO issues but is oftentimes linked to a buffer issue. Before we delve deeper in this interesting topic, first let us understand what Latch is. Latches are internal SQL Server locks which can be described as very lightweight and short-term synchronization objects. Latches are not primarily to protect pages being read from disk into memory. It’s a synchronization object for any in-memory access to any portion of a log or data file.[Updated based on comment of Paul Randal ] Latches and Locks are two key synchronization objects that can affect system waits and overall performance. They are quite complex in nature and quite a lot of efforts are needed to understand them fully. For the sake of simpler understanding, I would term latches as light-weight internal locks that are usually applied on in-memory buffer pages. Locks are for ensuring transactional integrity which you can control to a l...